Good stuff: A decent number of genuinely funny lines, and some sly references to classic movies. A cameo by Laurence Olivier from beyond the grave. The DVD has the story of the making of the movie, which you shouldn't miss; it's a great story of a creative kid plucked from obscurity to make his first movie with the likes of Jude Law and Gwyneth Paltrow.
Not so good stuff: the plot is aimed at a 13-year-old mentality. Somehow the special effects, while impressive, seemed to keep me at a distance from the main characters.