Sony Ericsson's first Android smartphone, the Xperia X10, arrived at my office Saturday - a day late, courtesy of FedEx. I've had a little less than two days now with this unlocked version of the device, and have been using it on AT&T's 3G network. Read on for my first impressions. Unboxing video coming soon - it's a long story, but I made some dumb errors while editing the vid, posted it, took it down, and re-edited. Now it's ready to upload, but as I'm at the airport awaiting my flight to Vegas for CTIA, I can't find a fast enough uplink to get the file up to the cloud. Oh, the travails of modern workflife.

All in all X10 is a nice device that could be very, very nice but suffers from some quirks and minor lags. Sony's custom user interface, comprised primarily of their Timescape and Mediascape apps, is nice but feels less revolutionary now than it looked when the X10 was first previewed some months ago. While the phone is powered by a 1GHz Snapdragon processor, it lags while loading certain apps - likely due to a combination of the outdated Android OS 1.6 platform and the network intensive nature of Timescape.

- Call quality is pretty good so far, but the earpiece seems kind of quiet. Voices on the other end of calls have been clear but low-volume; I had to crank the volume all the way up, and at that point could hear the plastic chassis of the X10 vibrating ever so slightly during a call.

- Battery life has been fairly solid, but I'm concerned about drain from Timescape connecting to Twitter, Facebook (and MySpace, if I used MySpace) to pull updates. Timescape is easily adjustable, though, to limit automatic network updates or turn them off entirely.

- The 4" display is very nice to look at. I'm convinced that 3.7" (Nexus One and Droid) is now the absolute minimum size for a high-end smartphone, and 4"+ is the wave of the future. X10's size nicely splits the difference between smaller devices and the slate-like enormity of the HTC HD2.

- While X10's display is capacitive touch, I'm finding it less responsive than best-in-breed touchscreens like iPhone, Nexus One, and Droid. I don't know if it's hardware, software, or a combination of both, but simple button taps aren't always registering for me.

- That said, when the system works, it's fluid and graceful. Kinetic scrolling is nice, SE's visual design is classy and geeky all at once, and photos look great on the 854 x 480 high-res screen.

- Mediascape is a really nice music app - perhaps the best music player to hit Android to date. The Web tie-ins to your local music library are nice (Web search, YouTube search, etc), but what I really like are the graceful but information-filled views offered while browsing your media library and playing individual tracks.

- Timescape is kinda neat, but much more suited to the casual social networking user than the power tweeter or Facebook fiend. Think of it as a much easier to view - if slightly less powerful - Motoblur. While it's nifty to see my contacts' photos along with their latest status updates or messages, I quickly moved the Timescape widget off of my main home screen panel and installed a proper Twitter client to better suit my needs. 

- My X10 came with both the Android Keyboard and something called "Standard Keyboard" pre-installed. Neither is very satisfying. While two-thumbed typing in widescreen mode is pretty nice thanks to the huge 4" display, the keyboard itself suffers from some strange design decisions. Comma and period deserve dedicated buttons, no? Luckily, it's super easy to install a keyboard replacement on Android.

- The device comes with a Sony Ericsson stereo headset but won't work with any of the third party headsets I've tried. Both my Etymotics and a pair of Shures I'm reviewing balked during calls and music playback - something about the "iPhone compatible" connector plug doesn't jibe with the structure of the X10's headphone jack. Standard headphones (without inline microphone) work fine with the phone, however.

- I tried the 8.1 MP camera briefly yesterday and results were pretty good given the harsh lighting conditions.  Video quality seemed quite good. I'll try to upload some shots later today.

- No word on possible upgrade paths to Android 2.1. I'll check in with Sony Ericsson this week.

More coming soon - I've got the X10 in hand for the trip to CTIA.