When I first decided to switch from iPhone to Android I had, for various reasons, 2 options open to me. SE's X10 and an Acer Liquid E. Similar stats, same processor (underclocked on the Acer) etc etc. However the X10 was rocking Android 1.6, while the Acer just went from 2.1 to 2.2 at the time. SE was slow and painful with their upgrades.
Fast forward to now, and I finally dropped the Acer and it's horrible build quality and went.. Sony Xperia (Play). I've gotten 2 firmware upgrades since getting it, and it even has a lot of nice touches specific to Sony like a Home Launcher that doesn't suck and features like xLoud. It's hard to believe this is the same SE that launched the X10 and then forgot about it. I've always liked the hardware, and now even the Software seems to be getting up to snuff.
I'm still a bit leary, I mean in a year they seemed to do a 180, and in a year they could do it again and go back to the old ways, but so far I'm liking it. What they really need to start doing however is releasing some dual core phones to keep up with the competition (that new Galaxy S 2 looks amazing), maybe even a newer Xperia Play that supports HDMI out (big screw up on their part in the original)