Shutter Island (2010)

My wife and I liked this movie. It wasn't great but it was pretty damn good. I never felt like I knew what was really going on. I always had inklings as to what was going on but never really could crack the code. It was nothing like I was expecting. Leo did a great job and the music really added to the whole experience. Also, it didn't feel like a 2.5hr movie. Definitely got my moneys worth.

EDIT: I'm surprised that people here knew EXACTLY what was going on. I had a pretty good idea about some of the twists but the entire twist I didn't guess.