I have to say that I was underwhelmed by this movie. It had been hyped up so much that maybe my expectations were too high. One reviewer commented that there was no descent into madness as they both started out as mad. Upon reflection I think that is one of the things that were a let down for me. As a character study there was very little character to study. I got did not get much sense of who these guys were as people. 

The movie was beautifully executed on a technical level. The cinematography and on location shots were incredible. The dedication to realism. The lenses and cameras used. The aspect ratio. The sound. And the acting. All superb.