I know that the original Psycho was a classic and remaking it was a mistake, ESPECIALLY a shot-by-shot remake. I think that that has been more or less proven by the rest of the comments here. But there's far more wrong with this movie than just that.
The first problem is the color. The original film was shot in black and white but, what few people realize is, the original was shot AFTER color film had been invented. The choice of black and white film was partially a budget concern, but it was also a stylistic choice of Hitchcock's. Now, this is not to say that the remake should have been redone in black and white, but the colors of this movie are all too wrong. The most predominant colors in the film are orange and green, particularly on Marion who is not supposed to be a flashy character. The bright colors make it look like a happy movie and, when horrific events take place in these color schemes, it looks like a cartoon more than anything and the audience is inclined to laugh rather than scream.
The second problem is the lighting. This is a dark dark tale which should be highlighted by dim lighting, but this remake seemed not only to fail in this but seemed to go in the OPPOSITE direction. Most of the scenes are very brightly lit, even at times when it is illogical to do so because it's at NIGHT!
Another obvious problem is Vince Vaughn's performance. Yes, he does pull off Norman Bate's awkwardness and madness quite well, I don't deny him that. But there is one element to the character that he failed to show: the softness. There should be a certain deceptive friendliness to the character, at least at first, which then fades away once we realize the truth about him. Beyond being a character trait of Norman Bates, this is a recognized character trait of ALL PSYCHOPATHS!!!!
There are a few good aspects of this film. Some of the performances are great. As I said, Vince Vaughn came very close to pulling off a decent portrayal of Norman Bates. Viggo Mortensen and Juliane Moore were great together and their chemistry was very different from the characters in the original, which was a welcome change. Anne Heche may have been atrocious but, unlike Janet Leigh who was untruthfully advertised as one of the biggest stars of the film, Anne Heche was given last billing in the opening credits.
I read on the cover of a copy of the Psycho novel that Gus Van Sant claimed this was not a remake of the Hitchcock film but rather a new adaptation of the original novel. I now wish that I had bought that book and saved the comment because, after seeing this film, that comment is quite possibly the funniest thing I have ever seen. There was no attempt in this film to disguise the fact that it was a rip off of the original, and it would be far more believable if Van Sant had tried to tell us that he was really a three ton ape from the planet Zafroomulax. So many shots were copied exactly without any actual thought as to why Hitchcock had composed the original shot in that way. Such as the scene in which Sam and Lila are talking while their faces are entirely covered in shadow. Hitchcock covered these actors' faces in shadow because he thought they were bad actors and wanted to hide their faces so nobody could see their awful performances, not because of any artistic or stylistic purpose.
In other words, my review is about as pointless as the movie itself in that it replicates something that's already been said. Like everyone else here, I reccommend you don't waste your time on this film and get the original.