SPOILERS
Didn't like this much and I hope its success doesn't provide the wrong kind of reinforcement for Scorsese and the Hollywood twist ending factory in general. Scorsese's got kind of an unsure grasp of Kubrickian creepiness, and I didn't really find the alleged b-movie touches "fun," especially since he continues to cast one of the most un-fun leading men this side of Russell Crowe. It was good seeing Max Von Sydow, Ruffalo, and a few others though.
As the ending stands, it's boring, predictable, and implausible, but the premise is kind of inherently hilarious. Everyone is playacting for the benefit of a dangerous maniac running around the island, putting themselves at huge, expensive risk... during a hurricane, no less? That's gold, Marty, gold! I want to see a remake from the POV of the orderlies, nurses and fake (?) patients roped into going along with this shit, preferably directed by a resurrected Robert Altman.