The Nexus S is the new Google Android phone. It is sold exclusively by Best Buy in the U.S. for the T-Mobile network.
This is my personal review of the Nexus S with pros and cons. I will update this page as I learn more.
I'm especially interested in the Nexus S because it is Google's premium phone and helps set the bar for developers and handset makers, so this review will emphasize things that I see as notably different from other premium Android phones.
Pros
Pure Android Gingerbread
This is the first widespread phone running the new "Gingerbread" operating system, version 2.3.
I prefer Android stock apps more than manufacturer add-ons such as Motorola MotoBlur and HTC Sense UI.
Most noticible improvement: the stock keyboard is much better than in 2.2 and I prefer it to Swype.
New hardware
Near Field chip (but no real-world widespread uses yet)
16 gig memory built in (but no way to upgrade or add an SD card)
Front camera (but no built-in video chat yet).
Cons
Ugly in several ways
Overall the phone feels "cheap" to me. Something about the mix of plastics and textures doesn't look well-built and doesn't feel well-built. I feel this way about all the Samsung Galaxy phones. For comparison the Motorola Droid X feels solid and unified to me.
The lower back has an odd bump that doesn't fit my hand well, doesn't fit into a generic case, and tips the phone slightly backwards when its on a desk.
The software has a pervasive lime green and flourescent orange color theme. Some people may like this; I personally think it is ugly and detracts from the out-of-the-box experience. I have to figure out how to change the color theme.
The buttons for Home, Menu, Search, and Back are rearranged from every other Android phone I've had, which makes the interface more difficult for me to use and more prone to me pressing the wrong button. For example, the Home button is in the lower bottom right. Also, I'm a left-hander and the Home button is hard to reach easily.
The curved screen seems to cause distortion, as if it's a lens of glass of variable thickness rather than truly a curved AMOLED; the top area of the phone has a fishbowl effect. [Addition: this teardown shows the curved glass vs. flat AMOLED, thanks to user JG]
Buggy in several ways
Right out of the box the phone had problems finding the T-Mobile network and the GPS. My Samsung Vibrant Galaxy S had the same problems, and the Nexus S has much in common with the Galaxy S. For comparison the network and GPS worked fine on my LG Optimus and MyTouch 4G.
The home button and search button seem to be broken: when I go into an app like the web browser, then press home or search, the phone vibrates but nothing else happens. The fix is to reset the entire Nexus.
The phone app shows an error message like "Cannot complete the call". The error dialog box is impossible to dismiss, and there is no way to dial another call. The fix is to reset the entire Nexus.
The three bugs above have been impossible to report so far or to get fixed because tech support is non-existent so far. T-Mobile doesn't support this phone because it's a Best Buy exclusive. Best Buy policy is to refer the customer to Google for any repairs, refunds, or exchanges. Samsung's help line says "Sorry our contact center is closed."
Slow in several ways
Slow UI: the graphics are jittery and staccato, as if the graphics chip can't keep up with scrolling and sliding. To my eye, the jitter is on par with the Galaxy S; it's noticibly slower than an iPhone 4. Edit: other people are reporting this too, and the issue seems to be that the Nexus S is not utilising a dedicated graphics chip, and instead trying to do all the graphics on the main CPU. Source. For comparison the iPhone graphics look perfect to me when scrolling and sliding.
Slow data: the data speed is terribly slow compared to the other new T-Mobile phones like the MyTouch 4G. This may be because the Nexus S uses the older, slower, busier network (3G-speed HPSA) whereas the MyTouch 4G uses the newer, faster, more availble network (4G-speed HPSA+). I see the Nexus S as about five times slower, which is significant to me because I use the phone for tethering.
Slow repair: T-Mobile says my Nexus S needs service to fix the broken Home button, which means mailing the phone to Google and waiting for Google to mail back a replacement phone. This could take several days or more, which is much slower than a normal same-day in-store T-Mobile replacement.
Conclusion
The Nexus S feels half-baked or rushed to launch. It's not an iPhone-killer, and in my opinion it's not a must-have phone unless you absolutely need pure Android Gingerbread or the Near Field chip.