Anyone who's seen Rocky or any other "underdog" type of story is going to pretty much know what happens before the film ends. Although it may be formulaic and predictable, it's excellent cast bring some freshness to the mix. The best thing about the movie to me is, I didn't once feel like I was watching a rapper try to act. Eminem is technically playing himself, but he still delivers a great performance.
Oh yeah, and the rap battles are funny as hell. :)