Shutter Island is superb! Well, if we had to put it in a genre it would be, as you have heard, Neo-Noir.
Film NOIR specifically refers to a group of films produced during 1940-1960.The story of a crime from the perspective of the criminals rather than that of the police. The setting is usually urban and dark.
NEO-NOIR borrows what it can from film noir: hard-boiled stories, protagonists, themes and darkly lit visuals – and leaves behind what it cannot appropriate from the popular culture of a different historical era
Why can't people grasp that not ALL movies fit neatly into one particular genre?
go to www.imdb.com and look it up.
honestly, your not missing anything. Shutter Island was a horrible movie, but if you still wanna watch it, I think it may be under Horror. I'm not rlly sure.