Harvey Keitel is certainly convincing as a seriously demented dude, but he doesn't have the strange vibrancy that Nicolas Cage brings to the role. The cinematography might be at fault here somewhat - I can't really put my finger on how exactly, but it seemed to me that the camera angles and perspectives were really ineffective in this movie. Keitel seemed awfully small and far away - you really felt like you were removed from all the action. Again, this could be because I saw the other one on the big screen and this one on my small tv at home, but still, it really felt oddly detached.
Also, the plot is a lot less exciting. In this movie, the story is rather simple - two guys rape a nun. The nun knows who they are but won't tell. Meanwhile, Harvey Keitel does a lot of drugs and also gambles. There's nothing particularly dramatic or compelling about it, and the various storylines seem pretty unrelated to each other, whereas in Herzog's version, there's a dense web of stories that all seem to permeate each other in various ways.
The Keitel version left me cold, for the most part - except for the last 5 minutes. Maybe just 3 minutes. They were actually quite interesting, and definitely upgraded the movie in my mind. Unfortunately, that 3 minutes comes after 130 fairly dull ones, so the payoff isn't really worth it.