I hadn't heard about the extra features in the Xbox version, but I knew it was exclusive to it for six months. It would actually make more sense to me if the extra stuff was on the GameCube version, as they have the extra six months to complete it.
I actually thought it was coming to all three systems, but maybe I'm just messed up in the head.
Anyway, yeah, the game looks really good, graphically. Good movie. I hope it'll be a good game.