I'm not sure how faithful this movie was, but it seemed word for word at times. That was a good thing. When Vince Vaughn came on the screen as Norman Bates I was concerned, but it worked out fine. It took about ten minutes to get over his idiosyncracies, but once I did it was smooth sailing. In fact, the whole cast was fairly interesting. I'm impressed that the studio took the high road instead of having this conversation:

Studio Dude 1: Let's remake Psycho. People love Hitchcock...and naked chicks in the shower.
Studio Dude 2: Yeah, naked chicks. How about this, Psycho mixed with Scary Movie.
Studio Dude 1: Only if Jackie Chan stars.
Studio Dude 2: Done.

I swear that must happen all the time. Anyway, they obviously made the right choice.