If you’ haven’t already made your decsison and reserved your copy, you may want to check out Kotaku’s head-to-head comparison of GTA for the Xbox 360 and PS3.
The analysis is exacting, since even they admit that the difference are almost microscopic. But for you performance and graphics wonks it’s really helpful.
It also may make you PS3 owners feel a little better, since that article was posted almost side-by-side with another that skewers the SIXAXIS controller for GTA use. Looks like you’ll be turning the motion controlls off.