I tried an x10 for my next phone, and to be honest android was a little too buggy for me, I had it for about 3 hours and like you do with a new phone, you play with the features, change things etc, and I managed to crash it, and it hangs ALOT when your doing several things at once.
I think when the next firmware update comes out, and they fix alot of the problems, it will be worth getting then, but at the moment its too ugh.
I prefer the Xperia x1, which the screen and camera in my opinion are way better.
I will point out the xperia uses the 'business' software from Sony, which is as different as Chalk and Cheese from the 'usual' sony software, so just because you like your K800, W995 etc doesn't mean you'll like the xperia as its a totally different beast. If you liked the P-Series phones, you'll like the Xperia.