Having seen Killing Them Softly, I felt compelled to dig up this earlier Andrew Dominik epic, which apparently launched Casey Affleck's career. It is quite a departure from both that and the much-earlier Chopper; the humour here is a lot more forced, so perhaps Jesse James had lessa sense of the absurd than Chopper.
I got into it somewhere around the 90 minute mark. Casey Affleck is indeed great as something of the mumbling psycho he later played in The Killer Inside Me. Brad Pitt almost becomes something other than Brad Pitt, sometimes for seconds at a stretch. The acting is excellent across the board, and the cinematography is brilliant, with striking use of light and angles by Roger Deakins.
As far as the story goes, we get an instance of the ancient archetype of betrayal. This is not really a western, at least not in the John Ford sort of way. The soundtrack is by Warren Ellis and Nick Cave, with the latter getting a cameo in a bar at the end.