Of the seemingly countless variants of the Galaxy S that Samsung's in the process of deploying around the globe, one stands out in a couple very unique (and important) ways: Sprint's Epic 4G. The Epic hangs on to a couple of the Galaxy line's most important characteristics -- namely the 1GHz Hummingbird processor and the 4-inch Super AMOLED display -- but adds in a sliding landscape QWERTY keyboard, support for the wickedly fast WiMAX network that Sprint shares with partner Clearwire, and a handful of other notable one-off customizations.

We've already taken a look at two of the other US-bound Galaxy S models -- AT&T's Captivate and T-Mobile's Vibrant -- but it shouldn't take more than a quick glance at the Epic to tell you that this is a very, very different beast. Becoming just the second WiMAX phone released in the States (and the first with a physical keyboard), this is a pretty critical release for Sprint at a time when its subscriber count is just starting to pick up after several quarters of decline -- and making things even more interesting is the fact that Sprint's first WiMAX handset -- HTC's EVO 4G -- is simply one of the best phones we've ever reviewed. In other words, yeah, you could say that the Epic's got a lot to live up to. Is it up to the task? Let's find out.

Packaging

Sprint has ditched the strange (or cute, depending on your attitude) "TV dinner" packaging of the EVO in favor of a more traditional box here. Boring, yes, but look on the bright side: unlike the EVO, this setup is easier to keep closed (assuming you care and you're going to hang onto it) because it doesn't rely on a flimsy cardboard sleeve to keep the lid on, and fortunately, they've gone with a really thick, sturdy, high-quality material for both halves of the box. Inside you'll find -- besides the phone, of course -- a USB charger, micro-USB cable (there's no cable permanently attached to the charger, a pretty common trend these days), and the same surprisingly decent earbuds found with the Vibrant and Captivate. Anyone intending to use the Epic for serious music use is still encouraged to bring their own headphones or earbuds of choice, but it's pretty cool that Sammy's offering buds in the box that are high-quality enough to include replaceable tips.

You also get an SD-to-microSD converter that you'll be able to use with the 16GB microSD card that comes pre-installed underneath the phone's back cover (though you don't need to remove the battery to get at it, which is nice). Why 16GB when AT&T's and T-Mobile's versions only include 2GB? Good question: turns out the Epic only has a little over 400MB of app storage internally -- not the capacious 16GB of the others -- so Sprint compensates by throwing in a beefy card. Though that'll work just fine for 95 percent of users, it's important to note that this means you can't get it up to 48GB of available storage by picking up a 32GB card. Since it's obvious Sprint tried to make this phone as "epic" as possible, it's unclear why they left out that internal capacity; the only thing we can think of is that they simply ran out of room with all of the phone's modifications over the standard Galaxy S like the slider mechanism, the LED flash, and the WiMAX circuitry. Hard to say.

Hardware

Of all the Galaxy S flavors we've seen, the Epic 4G -- despite its name and form factor -- might have the most nondescript appearance. Depending on your personality, that's either a good thing or a bad thing (for what it's worth, we liked it). The front of the phone is dominated by an expanse of black gloss rimmed by a matching black bezel, which makes it almost intimidating when it's sitting there with the screen turned off because you can't readily see the outline of the screen or the capacitive buttons below it -- just a whole lot of black with tastefully-proportioned Sprint and Samsung logos at the top and bottom, respectively. In fact, it's so black that it almost seems like you could be looking at the back of the phone.

Speaking of the back, Sprint got it right where AT&T and T-Mobile frankly got it wrong. It's a subtle black soft-touch -- not the Vibrant's cheap, glossy plastic or the Captivate's faux carbon fiber weave -- which gives you just a little bit of grip when you're holding it. The sparkling flecks in the back cover are actually one of the few concessions to style on the entire phone, and though we generally don't like our phones to sparkle, we'll begrudgingly admit that it probably would've been a bit too plain if they'd just done it in a flat black. Another place where the Epic wins over its Galaxy-branded cousins is just below the 5 megapixel camera, where you'll find an honest-to-goodness LED flash (more on this later). One very minor complaint we have about the back is that it pries off; we always prefer the sliding style because it involves less of that uncomfortable "I wonder if I'm going to break this" feeling you get when you're trying to yank a flimsy cover straight up and out, but considering how rarely you should need to get in there, it's basically a non-issue.

The sides of the Epic are where you'll find the only other blatantly stylish element on the entire phone: a thin chrome ring that runs all the way around, roughly in the middle of the edge, without extending into the keyboard area at all. We don't frequently say this about chrome, but it's tasteful and it actually works here. You'll also find the usual array of edge-mounted doodads, including a volume rocker on the left side, power and two-stage camera buttons on the right, and a 3.5mm headphone jack and micro-USB port up top. Like other Galaxy S models, the Epic has a neat retractable door to protect the port, a far better arrangement than the flimsy rubber plugs you usually see (though we still don't think micro-USB ports really need a lot of protection, considering they were specifically designed to be robust). The volume and camera buttons have plenty of feel, but the power button -- which is more flush than the others to prevent accidental actuation -- would be much easier to deal with on the top for a couple reasons: one, that's where you usually find it; and two, every time you press it, you risk accidentally sliding open the phone a bit. Considering how often you press power to take the screen in and out of standby, this is actually a topic worth discussing, but it's not a deal-breaker (and interestingly, we didn't like the design of the power button on the EVO, either).

The Epic's slide mechanism is a fairly heavy, smooth spring-mounted arrangement that feels solid with no wobble; on our unit there's just a tiny hint of give on the screen if you actively try to twist it, but we don't notice it in normal day-to-day use. That leads us into the keyboard, which is a completely flat, five-row type with a good deal of separation between the keys. You've got a good, strong "click" on each key -- no mushiness here -- but we definitely would've preferred a bit of doming, and we would've even been happy to sacrifice the separation in exchange for making the surface area of each key larger. The layout is a mixed bag -- we enjoyed having access to big Menu, Back, Home, and Search keys astride the letters, but the placement of Backspace and Enter gave us a little trouble... and we definitely weren't feeling the need for a dedicated smiley face key. Overall, we'd say that the Epic's QWERTY falls behind those of Android contemporaries like the myTouch 3G Slide (manufactured by keyboard specialist HTC, of course) and the Droid 2, but that's not to say that it's bad -- it's leaps and bounds beyond the dismal Moment, for example, and we imagine that anyone would be able to get fast and error-free on it within a couple days of use.

What surprised us the first time we picked up the Epic was how light it felt -- 15 grams less than the EVO, to be exact. Frankly, we wouldn't have minded it being a bit heavier, which leads us to wonder whether they could've squeezed in something beefier than a 1500mAh battery without causing problems. Though the Epic's screen is three-tenths of an inch smaller than the EVO's, the two are surprisingly close in length and width -- in other words, you shouldn't consider this over the EVO simply because you think it's going to be easier to hold. At 14.2mm deep, the Epic is noticeably thicker, but still comfortable in the hand (it's thin enough so that your fingers will likely still arch beyond the back cover) and it doesn't produce a ridiculous bulge in your pocket -- unless you're wearing something skinny and fashionable, of course. Then again, there aren't many smartphones that look good in that situation.

The Epic's 4-inch Super AMOLED display at WVGA resolution is exactly the same as the one you find on the Captivate and Vibrant -- and as you can probably guess, it's absolutely glorious. If you're not accustomed to these displays (even if you're already familiar with standard AMOLED), you'll be pretty shocked by the insane black level and the rich, dazzling color saturation that you get from these. Despite what you may have heard to the contrary, we'll echo what we said in our look at the AT&T and T-Mobile models that it still doesn't perform as well as a traditional LCD in direct sunlight, though it isn't completely washed out; in our experience, we could always make out the contents of the screen if we squinted hard enough. Since the screens are literally identical and the Epic won't be out until the end of the month, we might even recommend heading down to an AT&T or T-Mobile store beforehand and checking out the Captivate / Vibrant -- you'll get a good sense of what to expect when you pick up your phone, both from a display and a software perspective.

Below the display are four capacitive buttons -- the usual ones you find on Android devices: Menu, Home, Back, and Search, in that order from left to right. The buttons are actually below the Samsung logo, which means there's plenty of separation between them and the bottom of the display, but we found that they still suffer from a couple problems. First, they don't seem to be quite sensitive enough -- we found ourselves occasionally tapping twice to actuate them (we also noticed this on the touchscreen, suggesting that the entire capacitive surface could stand to be tweaked a bit). We also had the same problem here that we'd had on other Galaxy S models, which is that the buttons are backlit on a different schedule than the display. They seem to go out after five seconds and come back on whenever a button or the screen is touched, which is actually more distracting then if they simply stayed lit all the time. The behavior here might make sense if the buttons were more readily distinguishable without backlighting, but as it stands, they aren't -- we found ourselves leaning in to see the darkened icons more closely on a couple occasions. Basically, the simplest solution would've just been to paint on the buttons so you can see them without light (as Motorola and HTC usually do) and save a little battery power in the process.

[Update: Sprint has let us know that you can actually change the behavior of the button backlighting -- it uses the keyboard's backlight timeout setting, which is 6 seconds by default but can be set to match the screen. Problem solved!]

Speaking of battery power, we got 3 hours and 43 minutes of use from 97 percent power to shutdown with the phone in 4G hotspot mode while occasionally interacting with the handset, continuously streaming internet radio, and doing... well, you know, other "internet things" on our connected laptop. That bests the EVO by a few minutes, but we'd argue that it's within the margin of error -- especially since 4G battery life seems to be affected drastically by city and signal strength (we performed all of our testing in Chicago's Loop, where WiMAX flows like water). Interestingly, we checked Android's built-in battery monitor shortly before the Epic shut down -- the screen where you can see what components and apps have been draining your juice the most -- and were surprised to see it report that the display had allegedly been responsible for 55 percent of the drain, despite the fact that we had played with the phone for perhaps 10 to 15 minutes of the entire test. We suspect the app isn't properly accounting for the 4G radio, but that's just a guess -- and if by some odd chance it's accurate, that paints a pretty scary picture for the power consumption of these Super AMOLED displays. We haven't had an opportunity to complete a more traditional battery test in normal (read: non-hotspot) phone usage yet, but our preliminary testing suggests that you should have no problem getting through a typical day, particularly if you're smart about 4G radio management and you aren't keeping the screen on any more than you have to.

For 4G performance, this is always a tricky topic -- as we mentioned, network performance varies widely by location and other variables, but we were generally very happy both with on-device data and hotspot mode. Basically, it never stopped feeling "WiFi fast" both in terms of speed and latency, and that's exactly what you need to make a fantastic mobile hotspot. We were consistently getting around 4Mbps down and 1Mbps up during our testing; when we'd tested our EVO back in our review, we'd seen numbers as high as 7.5Mbps down and 3Mbps up, but checking it alongside the Epic revealed lower numbers more in-line with the Sammy, so we'll chalk it up to the network.

Camera

We weren't expecting the world out of the Epic's primary camera; given that other versions of the phone don't even ship with any sort of flash, it was obvious that Samsung prioritized a thin shell over heavy-duty optics. That said, we came away really happy with the stills we were able to capture. Maybe we were just having a good photography day, but whatever the case, shots looked clean and sharp with minimum artifacting at 100 percent zoom. Interestingly, we discovered the hard way that you get locked out of the camera app if the battery dips to 15 percent, so be sure you've got plenty of juice before heading out for your serious nature photography sessions.

Of course, the Epic ships with not one, but two cameras: the 5 megapixel primary on back paired with a weakling VGA cam on front. Make no mistake -- this second camera isn't to be used for anything but video calling, and considering that the quality of your video call is limited by bandwidth more than by camera quality, it'll work just fine there. Yes, the Epic's camera app allows you to toggle between cameras (the second camera is used for a "self portrait" mode), but trust us -- you really don't want to do that.

Video capture was less impressive than the still shots. The problem, really, is that this is advertised as a 720p recorder. Yes, true, you can toggle a 720p mode -- but to associate the quality of the output you get with anything you'd consider to be 720p is a complete fallacy. It's just roundly not good at that size. What Samsung probably should've done is cap the output to 480p and quietly offer 1280 x 720 as some sort of "extended resolution" mode, which would've gotten them off the hook at least a little bit. On the plus side, we found audio quality to be decent, though not quite as strong as the Droid 2 or Droid X.

Software

In most respects, the Epic 4G runs the same TouchWiz 3.0-skinned build of Android 2.1 that you find on other versions of the Galaxy S, which unfortunately means that we've got most of the same complaints. Many of our annoyances probably won't bug people who are just getting into Android for the first time, but some seasoned users -- particularly of stock Eclair or Froyo -- will be ready to punch Samsung's UI designers in the face after just a few minutes with the Epic. Our biggest issue is with the cartoonish, overly colorful appearance of everything, a problem exacerbated by the fact that this display makes bright colors look... well, really bright. For some reason, TouchWiz puts a seemingly randomly-colored square behind every app icon in the launcher, which -- to put it very bluntly -- looks stupid. We also don't like the fact that the launcher can only be toggled between a horizontal-swipe grid mode and a vertical-swipe list mode, which means that the standard vertical-swipe grid -- the one you've used on practically every other Android phone, ever -- isn't available.

Annoyances continue to the home screen, where Samsung has elected to permanently display a large panel number indicator (they use a 7-panel setup, by the way) immediately below the status bar. We don't mind when they're permanently displayed (in fact, looking at the way the Droid X and Droid 2 do it, we prefer it to be permanent), but TouchWiz's is huge -- large enough so that we actually think they could've squeezed in another widget / icon row if they wanted to. Sammy should've taken a cue from Google, HTC, or heck, even Motorola's first-gen Blur UI on the right way to implement this.

Generally, these manufacturer skins exist with the claimed goal of enhancing the platform's stock functionality, but we actually found a case on the Epic where the opposite is true: the phone's lock screen consists of a circle in the center of the screen that you drag up to unlock... and that's it. Gone is Android 2.x's ability to toggle ringer mute from here, a nice touch considering that you need to unlock, press power, and select a menu option otherwise. To our surprise, also missing is the neat "puzzle lock" mode available on the Captivate and Vibrant, which allows you to immediately view messages, missed calls, and the like by dragging and dropping a puzzle piece into its matching hole on the screen. It's not clear why Sprint would've decided to kill it off, because all that's left is a gimped lock screen (with the option of using Android's regular pattern lock).

As bloatware goes, Sprint and Samsung have done an okay effort -- just okay -- at holding back. When you turn the phone on for the first time, the installed apps consume two full pages in the launcher, which feels manageable. Besides the normal Galaxy S custom stuff like AllShare and MediaHub, you get Qik (with video calling capability, of course), Sprint Football and NASCAR, Sprint Hotspot, TeleNav-powered Sprint Navigation (which you might never use since Google Maps Navigation is included fully functional and unhindered), ThinkFree Office (lacking the Google Docs integration of the version available in the Market), and Sprint Zone, which is basically a one-stop shop for finding Sprint stores, checking out your account, and getting quick access to apps the carrier recommends. Sprint TV's also included, of course, but it just hangs on 4G whenever you try to watch a program -- we had to turn it off and use EV-DO to make it work, which is pretty counterproductive considering how much better it could look on a faster, lower-latency connection.

Apart from an occasional stutter while scrolling in the browser, the Epic's performance felt in line with what we should expect of its Hummingbird core -- in other words, it was generally responsive and smooth (Linpack scores ranged between roughly 7.6 and 8.2 MFLOPS). Of course, by Android's nature, it's easy to gum up the works by installing too many apps trying to do too many things at once -- but with a few of our essentials installed and the device fully synced to our Google account, everything sped right along. We did, however, notice an occasional hiccup with the phone's many window transition animations where they'd flash or stutter; it was hard to tell whether this was a performance issue or simply a bug, and in the end, we just turned them off and didn't worry about it. Also encouraging is the fact that the Epic is running Android 2.1 out of the box; we can only expect performance to improve once they've deployed 2.2 (it's not often that you'll hear us spin the lack of 2.2 into a positive, so relish in it while you can).

Surprisingly, the now-infamous AGPS bug is still alive and well right now on the Epic. We're not sure how Sprint can justify releasing it with this bug now so well-known, well-documented, and critical to the operation of the phone -- seriously, it cannot find you most of the time -- but we suppose it'll just get fixed at the same time as the remainder of the Galaxy S models in September. In other words, unless we see a quick firmware update prior to the 31st, don't expect Google Maps to work particularly well out of the box. Oh, and here's another bug: like the Captivate and Vibrant, the Epic doesn't seem to want to mount as mass storage. We weren't able to get it working in USB debugging mode on our Mac, either, though we were able to download media to Image Capture without a problem -- it seems as though the computer is treating the phone as a camera, not a drive.

[Update: We just spoke with Samsung, who told us that Google is now requiring that the "use wireless networks" setting for location-based services be turned off by default in Android devices -- in other words, no AGPS unless you manually enable it. Sure enough, we went into Settings, found that it was disabled on the Epic, turned it on, and we were good to go. No GPS bug!]

[Update 2: The fact that AGPS comes disabled by default is a separate issue unto itself, unrelated to issue with actual GPS satellite triangulation. See our full breakdown here.]

Wrap-up

Let's take our attention away from the specifics of this phone for a second. Speaking in more general terms, it's really impressive that Sprint has already managed to release two very high-end, exceptionally desirable devices built specifically to take advantage of its 4G network. In fact, we'd say that the Epic and the EVO -- even more than the Pre -- have vaulted Sprint from its status as an also-ran to perhaps the most gadget-savvy carrier in the US today. If you'd asked us 18 months ago whether we ever thought we'd be saying that, we'd have laughed at you. Of course, the Epic can't just be geeky, it's got to be good -- Sprint isn't out of the danger zone yet for subscriber churn, and it's going to need average Joes and Janes to buy these right out of stock. In other words, it needs to parlay the buzz that the EVO generated into a permanent slow burn, and the Epic is a critical part of that equation.

So is it the right phone for the job? In a word, yes -- the Epic 4G is a great device. Killer, even. Nothing speaks to us more strongly during the course of a review than finishing it and saying, "alright, I'm ready to buy this thing," and the Epic is on the short list of phones that has managed to do it. More than its Galaxy S siblings, it feels like the Epic has overcome its shortcomings -- notably the forgettable UI skin -- to shine, and it's a phone we could easily imagine using day to day. Only thing is, the EVO is also on that short list for us -- and the better camera, bigger screen, and $50 savings versus the Epic still make it our winner in this 4G shootout, though only by the thinnest of margins. Needless to say, if you need a physical keyboard and you're looking for the one of the most musclebound Android phones money can buy, we wouldn't hesitate to recommend it.