Hardware
You'd be forgiven for thinking the ATIV S was another of Samsung's many Android devices.
Much of that apparent kinship with the Galaxy S III is visible from the front: if it weren't for the Windows logo stamped prominently on the home button, you'd be forgiven for thinking the ATIV S was another of Samsung's many Android devices. It's that close. Spin it around, however, and you'll realize that it's not mimicking its siblings quite so literally. The brushed-metal effect on the back isn't real, but it doesn't have to be -- the result is a smartphone that could very nearly be called handsome, if a bit flashy. Build quality doesn't suffer, as it still feels very sturdy, and those swaths of metallic gray help minimize (though not completely eliminate) fingerprint smudges. Gorilla Glass 2 kept the front of the phone pristine during our testing.
Some may just like the feel of the ATIV S in their palms. While it's touting a larger screen than the 4.5-inch Lumia 920, it's easier to hold courtesy of its textured finish and thinner (0.34-inch), lighter (4.8-ounce) body. Your experience may vary, but we weren't as afraid of an impending drop when using Samsung's phone one-handed. For that matter, the interface itself is easier to navigate one-handed versus the Galaxy S III. The subtle design changes, along with Windows Phone's larger UI elements, reduce the chances of launching something by accident and put your intended target just that much closer.
Few will be surprised by the ports and controls around the device, which very closely follow both Microsoft and Samsung's guidelines. Not that this is necessarily a problem, mind you. Up top is the standard headphone jack, while the bottom has a typical micro-USB port. The main speaker is located on the back and isn't especially loud, although it's certainly audible from across a quiet room. We occasionally hit the volume rocker on the left by accident, but we had no such trouble with the right side's camera button and didn't struggle to reach the power button, like we did with the Windows Phone 8X. The capacitive back and search buttons at the bottom are almost too easy to graze, however.

The real highlight may be what's just under the surface. Unlike what we've seen with HTC and Nokia's highest-end Windows Phone devices, the ATIV S gives expansion a big, friendly hug. Pop off the rear cover and you'll find not just a space for a micro-SIM, but also a microSD slot and a removable battery. Some buyers may not need to hear anything more than this, really. We know many who refuse to buy a phone that can't grow with their needs, and they'll appreciate the opportunity to go beyond the 16GB of built-in storage (up to 48GB total) as well as carry a spare battery for particularly hectic days. The result won't be as capacious as 64GB models of the iPhone 5 or One X+, but it won't cost as much, either.
As we've mentioned, the ATIV doesn't usher in any great revolution in processing power. It uses the same dual-core, 1.5GHz Snapdragon S4 chip we've seen in some Galaxy S III variants, as well as many early Windows Phone 8 handsets. It sticks to 1GB of RAM rather than the 2GB of some of its Android brethren, but then again, there's less demand for the extra headroom. NFC is built in and once again uses the battery as the antenna.
Those hoping for a Nokia level of cellular diversity might be disappointed, though. In the Bell Canada model we tried, there's quad-band GSM, GPRS and EDGE (850 / 900 / 1,800 / 1,900MHz) and a similar number of dual-carrier, 42Mbps HSPA+ bands (850 / 1,700 / 1,900 / 2,100MHz), but just AWS (1,700MHz and 2,100MHz combined) for LTE. Variants for the US and elsewhere are poised to have either country-specific LTE frequencies or stick to 3G. As glad as we are that Samsung is catering to specific regions' needs, it's slightly disappointing to know that even an unlocked ATIV S sometimes won't reach its best data speeds on foreign carriers.
Display

We weren't kidding when we said the ATIV S had a familiar screen. This is the same 4.8-inch, 1,280 x 720 Super AMOLED HD panel from the Galaxy S III. That's both a blessing and a slight curse, in our minds. You'll ultimately get rich colors, wide viewing angles and deep blacks. That also results in the ever-so-slightly fuzzy look of a PenTile pixel arrangement. However, what we said for the Android device also holds true here: this panel is far better than previous generations, and the pixelated effect isn't really noticeable unless your eyes are too close to the 306-ppi image. Although AMOLED still doesn't have the best reputation outdoors, we could see it well enough on a sunny day with the brightness pushed up.
Next to its immediate Windows Phone 8 counterparts, the ATIV S faces a stiff fight. It has the biggest screen of the current bunch and doesn't have to worry about refresh rates when AMOLED has near-instant response. Still, it doesn't have the pixel density of the 8X, or the extra 48 pixels of width afforded by the Lumia 920. Anyone who lives in a cooler climate will appreciate the Lumia 920 LCD's glove-friendly screen, too. There were a few times during my mid-December testing of the ATIV S where I had to stop to avoid frostbite. We're fine with Samsung's approach when the screen is large and contributes to a thinner overall phone profile; we just have to accept that it's not the best in every respect.
Camera

Samsung recycled Galaxy parts once again with the ATIV S' dual cameras. Both the 8-megapixel, f/2.6 rear shooter and the front 1.9-megapixel, f/2.8 camera are lifted directly from the likes of the Galaxy S III and Galaxy Note II. On bright days and in good indoor lighting, that leads to photos from the rear camera that are sharply focused, with soft backgrounds in macros and accurate colors. The choice does maintain the reduced dynamic range, however, and the sensor is nowhere near earning trophies for low-light performance or image stabilization like the Lumia 920. Dark scenes without the bright (if slightly harsh) flash still result in either a lot of noise or pitch black elements. We had an opportunity to shoot with both the ATIV S and Note II for a while, and many images from both cameras were nigh-on identical to each other -- lumping the mostly good in with the occasional bad.