To be quite fair, the movie had its highs and lows. The highest parts, however, were the banter between the secondary characters. Rob's faces made the movie. The biology scene comes to mind.
Don't go see it if you are expecting to see an award-winning movie. If you want to be thoroughly amused, and if you've read the book, then buy your ticket and some popcorn, sit in the very back, and prepare to be amused with "This is the skin of a killer!" while he sparkles.