Like the later Harry Potter films, this film was mostly three teenagers running from one FX scene to the next. The plot didn't make scene. though if you have read the book that won't matter much. There was no character development and while the main female character in the book was interesting, in this film she was tough acting for the first 15 seconds and then she became standard issue girl who needed to be rescued.
The special effects were sometimes really neat.
My ten year old who loves the book thought the movie was pretty good.