The 360 version is definitely sub par compared to the PS3 one. For one thing, it runs in a lower resolution: 1024x576 rather than 1280x720. Apparently, the movie compression really shows during actions scenes. For a game whose designers thought graphics were more important than content (they basically said as much when they had to explain why the game had so few towns), this is an even bigger complaint than it would normally be.
Thankfully, I have a PS3.
Nonetheless, I'll be following DragonNinja's lead and buying it second hand. This FF seems to be almost as poorly received as the last one, and if the rumours surrounding it are true, then it's everything I feared FF would become, plus a few other things I never thought would happen in my worst nightmares.