I received my Splitfish FragFX V.2 for Playstation 3 yesterday, and first impressions are very good. The response in games I've tested (Bioshock, Killzone 2 demo) has been awesome. Much better than using the analog sticks, especially coming from the PC world. Strafing sideways is easy, while staying locked on a target, something that I find almost impossible using sticks. That said, it's not as good as a PC mouse, but I didn't really expect that. Ultimately the FragFX has to translate mouse movements into analog commands, and thus it will never give you perfect 1:1 movement. But it's good enough.
One problem encountered is that the frag button doesn't work, but according to Splitfish there will be a firmware update next week that fixes this. Recommended.