I saw people who appreciated this film and people who despised it, and I didn't understand why until I saw it and now I can finally have my say.
This movie is sufficient for me and therefore I can't give it less than 6/10, the screenplay is good and the film itself also flows very well, in fact one and a half hours of it flew by without even noticing, but the good part ends here. American Psycho is based on the final plot twist by the protagonist (that Patrick isn't really a serial killer who kills everyone he sees but is instead a simple desire he has because he wants to change his monotone Wall Street office work life but can't because of how coward he really is in life), which however doesn't work because we understand that it's all a farce ever since Patrick "kills" Paul Allen.
But also about the other people we encounter who interact with Patrick, even if Patrick Bateman really was a killer, how can they not see the two-sidedness of him, the strange way he behaves, in all respects? Even if his desire to be a serial killer were true, it would have been discovered from the first kill, a fact that takes away the realism from the film and makes it more than a thriller, a slasher...