I downloaded the demo on both ps3 / 360 and found ps3's colors richer and the contrast isn't as overblown which gives it more of a 3D feel, also if you look at the ground textures on both you can see more details on ps3 version regardless of tv / in game brightness / contrast settings. the only negative against ps3's is that the jaggies are a bit more intrusive as if its running in a slightly lower resolution. also there is a few occasions where the ps3 ver loses vsync which causes some screen tearing.
Tough call on which version I would buy, judging from the demo I really liked the way it looks on PS3 but the jaggies are a bit annoying. Pro's and Cons on both systems.
Game itself is pretty interesting I had fun after going through the demo a few times, especially after getting used to the controls.