The Princess Bride :: William Goldman
I’ve only seen the film once, and it was a few years ago, but I actually enjoyed it quite a bit.
This is one of the few films which completely captures not only the essence, but also almost all of the content of the book. On it’s own merits, and especially considering the base content of the book, the film is extremely well done. Part of this is because the movie includes the father reading the book to the son, which allows for narrative interruptions without loss of continuity.
This is one of the few cases where I can’t say I got more from the book than I did from the movie.