I've tried a few games since getting my phone, and have a few findings:
I like Pixel Rain - it's a simple game but it's interesting and is a good time waster - since the levels are short puzzles, it's good for doing something without having to be immersed.
I also like Osmos, the concept is pretty straight forward, but it's a nice mix of concepts in a straightforward game that looks quite nice.
Defense Craft and Midieval Empires seemed shallow and a little difficult to use the interface of... I didn't get past the demos.
I've also spent some time with Chess Free by AI Factory, it's a straightforward chess game, but the AI is pretty good (and I'm pretty bad), so if you're not a chess player, don't expect to win much even on the easiest difficulty. It's nothing fancy, but it's nice to waste some time on something intellectual now and then.
Robo Defense seemed interesting... but it's a little static. The visuals are nothing fancy and it's a pretty simple game, I didn't get past the demo, but it's not uninstalled.
Minecraft is a nice idea, but with only the basic creative mode you can't do much. The controls are ok without the Xperia buttons, but they're a bit of a pain. I'm hoping it gets to be better when survival is added.