"comic relief in a movie this dark"

I think that's the best thing about it, the satire of corporate America, in which having a perfect business card and and a perfect haircut really are not much different than committing murder. All are techniques of getting to the top of the status hierarchy, which is what matters, and what matters even more is that others see you that way. Reality doesn't matter, only perception. This movie captures that sense of dazed and confused unreality.

I also loved the musical version, with former Doctor Who, Matt Smith, as Patrick Bateman, because, given that it was a musical, it was more vein, more camp, and even more humorous.

Still, Christian Bateman's sheer intensity, his greatest quality as an actor, hugely enhances the humor of this movie. It is hilarious that someone so intense can be so damn serious about such petty stuff as cards and haircuts, and it is also hilarious that someone so intense can be so lost. Not only is his morality blurred, but, as in the book, even his sense of reality. I suspect he's better than DiCaprio would have been, as DiCaprio, while a great actor, is not naturally wound so tight.

I saw Huey Lewis live back in 2013, and all I could think of was Patrick Bateman. :)