I've just finished watching the original film (uncut version), and i was really disappointed with it. It wasn't nearly as shocking as it's made out to be. Yes, the rape scene is nasty (rape of any kind is), but imo the rape scene in the 2009 version was more uncomfortable to watch and thus more shocking. The acting in the remake was also much better (the mother and father finding the daughters dead body in the original nearly made me laugh, where was the emotion at discovering their dead daughter??). Also, the characters were more fleshed out in the remake and it seemed more believable. I'm sorry, but the remake is infinitely superior and i fail to see how people could call the original a "masterpiece". I can understand that it was probably "good" back in the day, but the remake just changed the film for the better (imo of course). Not to mention that the whimsical music that was played throughout it and the dim witted cops adventures totally ruined any atmosphere of menace, never once did i feel tense.
Maybe if i'd watched it first before seeing the remake i might have appreciated it more but i think this was one film that was in need of a remake (and i'm normally someone who loathes remakes...).