Have you had any of the Xperia phones before? I've got an Xperia arc s and am looking forward to upgrading it in a few months. It's pretty good, but has some major failings which bug the bejeezus out of me. (Such as when I hold it to my ear while making a call, and the screen goes blank, as it should, it doesn't always UNblank when I take it away from my ear. Very irritating, and sometimes I need to remove the battery in order to end the call!!) I've even tried Rooting it and putting a whole new Custom ROM onto it, "Ice Bean"), but it's not helped. So the Z might be on my mind if an upgrade to it is possible.