Just my thoughts...
I really feel that this has more in common with game than a movie. It tries for a serious murder story but crosses the line of reality with GTA-like police chases and having the player kill people on more than one occasion without any serious weight to it.
The origami killer being Scott Shelby was a great twist that I was not expecting, though on replaying it, I realized that I should've. There was so much hinting and foreshadowing to it, but I (and probably many of us) ignored it because he was one of the few likeable characters in the game world.
It was particularly odd when he noticed the antique store owner dead and closed the window instead of looking outside to track whoever had done it. I feel stupid for not raising more than a suspicion when he murdered scores of security guards. The scene where he cares for a baby, yet is a killer, does make sense in that his entire reason for murdering is paternal.
Oh, and red herrings. The wealthy playboy Gordi is one for sure, but an acceptable one. Ethan's blackouts early in the game (a vestige of a cut paranormal backstory) made me think he was on the same drug as the FBI agent Norman (nahman) Jayden.
Backstories like Madison's post-traumatic stress disorder from war were cut to smooth the pace of the game, which is really smooth to be fair. But you give up something either way.
I do think the game is a bit racist and sexist. The only non-white character is beastly and uneducated. And, women are mostly portrayed as strippers, prostitutes and peoples whose lives were fractured by the absence of men. The scene where Madison had to strip for a sleazy night club owner was very uncomfortable.
I know the game wants to bare all, even uncomfortable things, but I still think this game is too indulgent in tits-and-gore to be on the same storytelling level as movies and novels, but as a GAME, it's really fun.
It does have some flaws, but it's also one of the most unique and interesting games I've played this gen. Definitely one of my favorite games of 2010. I'll take an amazing game with big flaws over a good game that has no big weaknesses.