xperia play works well for what it is, an android phone with a game pad. the analog touchareas suck. but it is really good for playing snes games on the go(it has all the right buttons and a nice screen for that). it's not a bad android phone either.
I own a Play and just got a Nexus 4 for some perspective, and what I've decided is that they should have bit the bullet and put more CPU and RAM in the Play, even though it would have raised the price. They should also have offered an accessory to make the phone fatter and add more battery, which would have been easy enough to do given the location of the ports. Since they cheaped out particularly on RAM, it was too difficult to shoehorn ICS onto the device and it was abandoned when the rest of the Xperia line got upgraded to 4.0. And since the device was so thin, it was outright painful to use the touchpads, which were also just not very good.
If you've played games on CM on the Play, then you know that it's not really that fantastic because of the lack of free memory. If there were any hope of getting KitKat on it then it would be worth keeping as more than an emergency backup phone. Also, I found that with many ICS or JB ROMs, doing things like hanging up after a voice call would earn me a free reboot, while stock-based ROMs using LuPuS GB kernel tend to be rock solid, e.g. AuroraPlay. Also, touchpad driver problems even with the fancy fix and activator. Not really worth the effort.