In the last week I've seen two movies, one based on a classic, world-renowned, nearly flawless novel, the second based on a collection of SF tropes that have been around for fifty years. The second movie was the good one.
Brideshead Revisited (Evelyn Waugh) is one of my favorite novels of all time. The current version did not need to be made, since the BBC had already done a marvelous mini-series starring Anthony Andrews and Jeremy Irons. If the current version somehow had to be made, it didn't need to totally reverse characterization (in the book Charles Ryder says Brideshead Castle should go to the heir presumptive; in the movie he covets it throughout for himself.) The film did not need to polarize complex and subtle characters into good-bad. It did not need to change the ending, and thus the point of the entire book. It didn't need to do those things, but it did them, and the result is an unqualified disaster. Do not see this movie.
On the other hand, Wall-e is charming. It contains no ideas that Fred Pohl, Cyril Kornbluth, or Arthur Clarke were not exploring in the 1950's: a consumerist society growing fat and powerless, the exodus from a ruined Earth, the survival of machines after we leave. But Wall-e embodies these ideas in robots that are inventive, appealing, and just plain fun to watch. There are sly nods to 2001: A Space Odyssey, to Star Wars, to less well-known SF. When I left the theater, I felt like humming a quick chorus of "Everything Old Is New Again."
Was this partly because my expectations of Brideshead were greater than for an animated movie for kids? Undoubtedly. But the contrast isn't totally a matter of expectations. It also grows from film makers who treat their material with both respect and pleasure. Waugh deserved better.