The movie's handling of Anakin's descent into the darkness is, to put it lightly, pure poo. The novelization is infinitely better, goes into far greater details, and talks about the demons Anakin has to fight, Sidious' skills of manipulation, and how hurt Obi-Wan really was when he had to leave Anakin for dead.
The movie is nothing but flashy graphics and a few lines to hide that fact. (However, Lucas did get the flashy effects very right. As crappy as the movie was, I still enjoyed it lots.)