The PS2's blurry graphics and slowdowns water down the experience by a whole lot, and the extras aren't worth it. That's coming from someone who loves the game and the series, and finished RE4 more times than he can count on both consoles.
Since you don't have a Wii, get the GC version. Prettier, smoother, better. The only con about this version is the disc-swapping (2 mini-DVDs), but personally I don't see that as much of a problem.
PS: In case you REALLY are that interested in the PS2 extras, I'd reccommend renting the game and getting a full game save from a friend.
PS2: Heck, just noticed you bought the GC version already lol. Anyways, great purchase! Enjoy one of the best action-adventures ever made.