As a huge gaming fan I was interested in the Xperia Play right from its first announcement, and whilst it doesn't quite live up to all the hype that surrounded it, it is still the best smartphone you can buy for gaming as the dedicated gamepad really does make all the difference.
While it is PSP/Sony certified it doesn't run PSP games, which is the biggest disappointment for a lot of people. But it will run Playstation 1 games and its own selection of Android games enhanced for the Play, so all is not lost.
The bundled games are better than you often given for free and for once they are all full versions and not demos or time limited. One thing to consider is that when you first launch any of the Play specific gaming titles (already installed or new purchases) the game will then need to connect to the internet and download a sizeable amount to the phone's SD card to complete the installation. This can be anything from 20MB to over 600MB, so make sure you are connected via Wi-Fi when you do this or you could quickly eat up your data allowance.
As for the rest of the phone, it might not be as fast as the latest dual core models like the Galaxy S II, but it is more than fast enough and responsive for everything I've tried on it so far, and with Android 2.3 installed it is a very nice experience. It also has a very nice display.
A problem a lot of Android phone owners have is updating their phone's OS to a newer version. On the Galaxy S I had this very issue with the PC software not able to communicate with the phone properly and failing to upgrade it. With the Xperia Play Sony have added the ability to update the phone's OS on the phone itself OTA (over the air), so you don't need to even connect it to a PC. Just go into the Settings and ask the phone to look for any updates, and if it finds them you can let it download the update and perform it all from within the phone itself. I've already tried this with the Play and successfully updated to 2.3.3 so that is good needs and a simple solution compared to requiring PC software to perform the update.
And Sony are supporting this phone for the moment, unlike some others. 2.3.4 is due out as an update in October, and more updates due in the new year, so all good news. The 2.3.4 update will be adding swipe support for typing, and also sweep panorama creation.
Sony have also put their own custom UI on top of Android, much like HTC and Samsung do with their phones. I personally prefer Sony's approach as it is cleaner, but that is personal preference and up to each person to decide. I also like their Timescape widget which lets you quickly see your latest PMs, twitter and facebook feeds, news, and anything else you want in a scrolling stack of messages on the homepage. Nice feature.
Finally, if you are retro gamer, then the Xperia Play is a great choice as there is a large selection of emulators available for Android, and all I've tried so far allow onscreen controls to be hidden and keys to be assigned to emulated controls, so the Plays controller comes into its own for this. And all the emulators I've tried so far work very nicely too.
You also get a 16GB SD card free with the Play so plenty of room to keep you going for some time.
So all in all I highly recommend this phone.
If there were any downsides to this phone it is the weight, which is noticeably heaver than say a Samsung Galaxy, but not so much that it is a problem.
Also the camera is only 5MP, compared to others Sony make like the Arc which has an 8MB camera, but it still takes nice images, and if you really wanted to take more professional photos you would be using a proper camera anyway.