The original album was a semiautobiographical story by Roger Waters set to music. It explored the reasons why a person might decide to build a psychological wall around himself, having determined that the pain life can deal you is not worth the few moments of pleasure, so it's best to just shut everything and everyone out. It necessarily dug into the death of his father, his overbearing mother, his crappy schooldays, and his lousy luck with women. It was monumentally depressing, but had some good music and was great therapy for Waters to write and produce with Pink Floyd.
When they made the movie of it, they apparently decided that if depressing and twisted is entertainment, then making it ten times as depressing and twisted would make it ten times better. They were wrong. I think the album is great, though I don't listen to it as much as I used to. The movie has some good ideas, but they just took everything way, way too far.