Ars Reviews The T-Mobile Galaxy S II

"Despite its extra 300MHz per core, the T-Mobile version of the Samsung Galaxy S II is no faster than its counterparts on other carriers, according to our tests."

Ars Technica has a nice review of the T-Mobile Samsung Galaxy S II - with a bunch of nice performance benchmarks to take a look at. Depending on how you look at it, it's positive or negative (Negative in comparison with other carrier's versions of the phone, positive when compared to earlier versions of the Galaxy S).