Films based on literature are sometimes close enough to the book to be literature themselves--even when the tale is dark. I come away knowing I've read and seen a great job of craftsmanship that was thoroughly capable of making me better for having had the experience.

The films that offend the hell out of me are the ones that are based on things that people actually do believe is true. The Exorcist was that kind of film to me; manipulative in a rather heinous sort of way. As bad a mugging someone walking down the street.