If you've seen any of David Cronenberg's movies, then you should know that his movies contain some nasty material. "Maps to the Stars" is no exception, but this one features a different kind of nastiness. Cronenberg's previous movies showed things like mutated children, exploding heads, a man turning into a fly, a drug addict's hallucinations, and the revelation of a family man's former occupation. "Maps to the Stars" features a scene that looks very much like a scene in a Cronenberg movie, but most of the violence here is emotional violence. Every character is REALLY screwed up. That's to be expected in a movie about Hollywood, but Julianne Moore's character is like a knife against your face.
In the end I thought that it was a good movie, but not a great one. The whole movie is like a kick in the gut, so I should remind you that it's not for the fainthearted (no Cronenberg movie is).