Norman: "You eat like a bird."
Marion: "And you'd know, of course."
What can I say about this movie that hasn't been said dozens of times? It set the bar in so many ways. This movie is where "slasher" flicks came from. Norman Bates was the first of several movie killers to be based (quite loosely) on real-life killer Ed Gein. Robert Bloch wrote the book Psycho just two years after the story broke, and Hitchcock's film came out the next year.
Hitchcock worked out a gimmick with theater owners that audience members were not allowed inside the theater if they arrived after the movie started. I cannot imagine what a movie audience in 1960 must have thought about this film. There are so many elements that just were not done in the movies of the time, as well as topics that were not heretofore explored.
One of the key things that makes Psycho such an interesting (and disturbing) scary movie is the fact that the character we think we're supposed to sympathize with is killed in the first half of the film. This throws the audience off-balance and leaves them with no one else to relate to but Norman Bates. In a way, we're on his side. For example, when he puts Marion's body in the car and pushes it into the bog, he stands there watching it sink and it stops for a moment, and I'm literally afraid that he's going to get caught. I think part of the reason he gets our sympathy is because he's played so well by Anthony Perkins. He's a very sympathetic character, in a lot of ways. I think my favorite scene in the film is when he fixes a sandwich for Marion and they have the conversation in the parlor. He's just so friendly and innocent, with his trusty umbrella and aw-shucks smile.
I'm no good at talking about all the technical stuff, but it's obvious even to me that the movie is a technical masterpiece. It looks so clean and bare-bones, which makes it feel more real, I think. This is such a great film - regardless of the genre. It's like the Citizen Kane of suspense movies.