GSMArena reports some pretty good things on it. I quite like it. Comes with Android 2.3 which will eventually be upgradeable to 4.0 which i think is ICS (latest). Only downside from memory is Sony are usually the absolute last to get the SW updates so while everyone with their Samsungs and HTC's and the like are on the latest software, the poor Sony users are stuck with the old SW for a couple of months
I think Nurb and dglewis were xperia users at one point and had to wait forever to get their updates