It's definitely fun if you can get hold of a copy/don't mind dropping the money for the amount of new video you're getting.

A friend of mine knows way more about both the movie and the books than I do, and she told me that the movie was originally going to be a lot closer to the books. The author herself told Dreamworks that she'd rather they make a good story than follow the books to the letter, and they took her at her word; she apparently is quite happy with the results!