I liked t Chess Pro when I reviewed it many month ago. It had good clean graphics, and was a real challenge to play. One of the most frequent requests was for Game Center integration, and that has been added in the most recent release.
Also interesting is the addition of support for the iPad 2 dual-core processors. It's the first use of dual-core support I've seen in an iOS chess program, and it's most welcome. t Chess author Tom Kerrigan told me the engine runs 50-80% faster, and he adds that if there's a good move to be found for the current position, the app will find it much faster.
I hadn't played t Chess for a little while, but this new version did seem snappier on the iPad 2. The Game Center Support is most welcome. t Chess is a universal binary, so it runs on any iOS device, but of course dual-core support is only on the iPad 2.
If you want to get a feel for t Chess, there is a 'lite' version you can try, but without the dual-core feature. t Chess is US $7.99. Given the excellent feature set, and the built-in documentation, I find it well worth it. Buyers should note that t Chess does not auto-detect a dual-core iPad 2. The feature must be enabled in the app settings menu.
My only gripe is that the icon for the app still shows a graphic of a crystalline chess set that is not an option to select for gameplay. The options the app provides are just fine, but I'd sure like to see the nice one illustrated above on the iPad screen.