I'm surprised at those that think the book isn't good. I think it's one of Priest's best works, and he's a fine author. The similarity ends in the name, honestly, and that the characters are fundamentally named the same. OH.. and that the two main characters are competing magicians, of course.
I don't get calling one better than the other. If the movie had been made too faithfully to the book, it probably would have to be a mini series. Either way, it wouldn't have been very cinematic, in my opinion. They both work perfectly for their respective mediums, and it's probably best to say the movie is inspired by the book. But this is one of, if not THE, finest adaptations of a book put to film. How many movies made out of books really capture the aspects of the book that you love? Here you don't even worry about that because it's a pretty different, and more focused, take on the source material.... and the movie is better for it.