Outside photo quality was high as well, even when I shot under the weak winter sun and overcast skies of New York. I was able to capture images of wily, quick-footed children as well. The only real complaint I have is that the Z1S' camera takes its own sweet time to focus, which forced to me to fire many shots in a row for fear of missing the action. I also noticed that the camera's shot-to-shot speed was sluggish, at about a second between consecutive photos.
Equipped with a feature-rich camera app, the Xperia Z1S certainly boasts lots of shooting modes and special effects such as HDR, burst mode, and face detection. One really quirky effect is the camera's AR mode, which lets you add virtual items such as T. rex dinosaurs, prehistoric foliage, and cartoon aviator goggles to unsuspecting people in your photos.
The most interesting camera feature to me though is what Sony calls Background Defocus, essentially a way to artfully blur the background while keeping subjects in the foreground clear and crisp. I can say the feature achieves moderately pleasing results though the look is obviously artificial.
Core components and software
Sony grafted its own proprietary skin on top of the Xperia Z1S' Android 4.3 Jelly Bean software. Inherently Sony's special sauce isn't too distracting but I much prefer stock Android, which is more intuitive and easier for me to navigate.
Driving the phone's operating system is a robust 2.2GHz quad-core Snapdragon 800 processor linked to 2GB of RAM. You also get a standard of 32GB of internal storage, a roomy amount especially considering the microSD card expansion slot.
In everyday use, I found the Xperia Z1S able to handle its Android 4.3 Jelly Bean with speed and agility. Frankly, that's saying something, since the Sony smartphones I've used in the past, including the Xperia Z, were saddled with underpowered mobile chips. This is emphatically not the case with the Z1S.
Thanks to its cutting-edge Snapdragon 800 silicon, the device notched a very high Quadrant benchmark score of 20,809. That beats, though barely, how the LG G2 (19,050), Galaxy S4 (11,381), and HTC One (12,194) fared on the same test, though it doesn't beat the Galaxy Note 3 (23,048). Its Linpack result of 1,088.2 MFLOPs was equally impressive.
I tested the Sony Xperia Z1S on T-Mobile's GSM network in New York and in my experience the phone delivered rock solid, if not outstanding, call quality. People I chatted with described my voice as clear and easy to discern, though they also detected a faint background hiss. On my end voices came over richly and with lots of lifelike presence but the earpiece didn't belt out copious amount of volume.
The biggest difference between the Xperia Z1S and its Xperia Z1 global counterpart is that it's been specially tuned to support T-Mobile's American flavor of 4G LTE. As a result the phone enjoys a fat pipe to swift wireless mobile data. In New York where I tested the Xperia Z1S I clocked average downloads at 17.8 Mbps. Uploads rolled in at a nimble average clip of 16.8 Mbps.
I managed to squeeze a satisfying amount of run time out of the Sony Xperia Z1S. Sony claims the phone and its 3,000mAh battery should power the Z1S for 6.75 hours of video playback while talk time is rated for 15 hours.
My tests fell in between these assertions. The device powered through CNET's video playback battery drain test for 10 hours and 32 minutes before calling it quits. The Galaxy Note 3, however, persevered for a long 15 hours when tasked with the same challenge.
Judging from its strong presence at CES 2014 where the company unveiled the Xperia Z1S, Sony's leadership has high hopes for this device. I've followed Sony for years and at the company's CES keynote, I could feel CEO Kaz Hirai's intense yearning for a return to Sony's "good old days" of mobile products people actually wanted to buy, such as the Walkman, Discman, and the first PSP gaming devices. Hirai trumpeted the Xperia Z1S as a product only Sony could make, one that draws on the firm's many areas of deep engineering expertise, and said it "truly is the best of Sony."
I certainly agree that the Z1S, like the nearly identical global Z1 model before it, is a powerful mobile machine and a device that flaunts a sleek style that's distinctly Sony. Sadly though, not even the smartest design nor fastest components can make up for a poor screen. It's a critical handset oversight: a phone's screen is as crucial as its software and battery life. That's why I'd strongly recommend competing devices on T-Mobile such as the Galaxy Note 3, Nexus 5, Galaxy S4, or even the HTC One. And like I said, it's just too bad T-Mobile didn't pick up the Xperia Z1 Compact instead.