Once again Scorsese has created a master piece. Shutter Island is fantastically directed, and subtly brilliant film. The plot is brilliant (no surprises there for anyone who read the novel – worth reading if you haven't, I think it's even better than the film). The acting is, well, also brilliant. di Caprio is great as Teddy Daniels, and Ben Kingsley, well he's perfect as Dr. John Cawley. The tone of this film is perfect. The subtle hints at the reality of the plot, of Asheclliffe Mental Hospital, of Teddy himself, are executed with mastery and precision.
There's not much more to say, except buy it, and experience it yourself. 5/5.