Unfaithful book adaptations that are great movies

Peyton Place (1957) -- skipped the trash and made it come out almost uplifting

Watchmen

An obvious one is The Godfather--a film classic that was produced from a turgid pulp novel. Jaws would be another.

Frankenstein (1931) is way different from the book.

The film version of The Prestige (2006) omits the modern day framing story of the book, and makes some other changes. Christoper Priest, the novel's author, published a full-length book called The Magic in 2008 to give his detailed opinion on the movie.

Priest wrote, "I liked what I liked much more than I disliked what I disliked, and found many scenes admirable. The opening is particularly effective, as is the presentation of some of the magic. There is sensitivity and skill throughout, but not flashy, show-off skill, as has been apparent in some of Nolan’s more recent films."

I read the novel The Prestige, and own both the book and the film. Personally, I didn't miss the modern day framing story, and thought the film did an excellent job, as the structure of Priest's book would have made a more literal cinematic retelling difficult.

Skip the awkward and embarrassing sex scene between Hooper and Mrs. Brody, if you do.

Of course they don’t have sex in the movie. Spielberg cut out that entire cheating subplot.

One reviewer from the 1970s commented that the first half of The Godfather novel was pretty good but at some point Puzo stopped "writing" but kept on typing. The movie, however, sustains its value to the very end.