I've heard a lot of reviews saying this was a bad movie. I disagree! I don't know if any of these people have read any of the books, let alone Hannibal Rising, but I loved the movie. Given, it seemed like Thomas Harris wrote the book strictly for the movie, but I felt this movie was made to have people understand how Lecter, "the monster" was created.
Yes, Lecter is irrational and that's the point. Hannibal Lecter is suppose to be distant because he's a psychopath. He's suppose to be apathetic. Some people mistook that for bad acting.
Comparing the movie to the book...they were about 85% compatible. Minor changes were made, but nothing too critical.
I think some people are quick to make this movie out to be horrible because they really are milking the Hannibal Lecter story, but I felt it to be a decent movie.