The acting - Sean Penn, Benicio Del Torro, and Naomi Watts, all do a fantastic job. Not as 'show off' as typical good acting sometimes is.
Like Memento, the scenes are not offered in chronological story order. However, there is no clear alternative structure either. Instead you have to construct the story in your head, which you manage to do by about half an hour into the film, and then hang each scene onto the narrative that you have constructed.
This has a couple of immediate benefits. Firstly, it means you have to pay close attention to the scenes. Secondly, some scenes remain ambiguous: has he just learned he is going to die, or that he is going to live?
Quick summary: an intelligent well crafted film, which possibly would not stand intensive scrutiny
