I guess when you base a movie on a book you have to try to honor it. This movie had a lot of detail, nuance and action. I could see that people could get confused along the way. But I thought it was a very clever plot, and pretty well done. It's dark humor and over the top action was intended, but by looking at the general reviews in this thread I can see that many people did not appreciate it.
As a side note, I saw it with dolby. It was quite loud, in the way but sometimes obstructs you hearing the dialogue. Maybe it was just the mix on the movie. It only happened a few times