Shutter Island: Did he or didn't he?

Martin Scorsese's new film is like an amusement park ride that twists and turns, then weaves back on itself, while all the time plunging you more deeply into menacing, forbidding darkness. It's about as nuanced and subtle as a James Patterson novel. But how much fun are they!
Leonardo DiCaprio is perfection as a U.S. marshal sent to an island prison for violent offenders to investigate the disappearance of an inmate. What he discovers — or thinks he discovers — begs the question: Are these inmates, or patients, receiving benign treatment under the stewardship of Ben Kingsley, the head psychiatrist? Or... is he conducting Nazi-like experiments on them?
The movie is set in the early 1950s, a time when mental illness and its treatments were shrouded in fear and ignorance, and it flashes back to the '40s and the marshal's hellish World War II experiences. And then there are the haunting dreams about his dead wife. He experiences migraines and visions. Is it in the food and cigarettes he's been given?
Critics weren't kind to "Shutter Island," but the Movie Slut found it fascinating. It made her think about the nature of violence and whether we are all capable of such acts. Pretty scary stuff.