I have had good 1 week with X10 and honestly SE seems to have tried to bite too much than they can handle with their first android device. They just tried to do too many things on Android 1.6
Rather than long descriptive post, I will simply list down the issues I have with this phone.
Physical Issues.
1. Built Quality : WTF was SE thinking using this kinda plasticky body on such expensive high end phone. Thankfully its not a flimsy plastic, but still disappointing.
2. Speaker volume : too low.
Software Issues
1. Missed call and SMS notification is super buggy. Sometimes it simply does not give the notification of unread sms or missed calls.
2. Timescape ( the custom app that manages all social networking, mail etc ) is super laggy. its fantastic, but SE needs to sort it out and make it more fluid to use. Its very unpredictable. It will work nicely sometimes, and slowly other times.
3. Phone has sudden slowdowns after you use Timescape for some time.
The screen is not really an issue. Sure AMOLED screens look richer and have fantastic blacks, but TFT has its benefits. The screen on X10 is brilliant for a TFT screen.
And then when you switch over to Desire and its polished, smooth SenseUI, and everything just works smoothly. I havent yet tried updating this X10 firmware ( as its not my phone ) but SE better fix the software issues fast.