I probably shouldn't have liked this movie as much as I did; it got a critical drubbing. The plot is complex, involving a large number of bizarre characters; it's hard to keep straight exactly who's on which side and what their goals are. Doesn't matter much, though, since the main purpose of all that is to get nearly all those characters inflicting deadly violence upon one another.
The movie does have a unique premise: a Vegas magician, "Aces" Israel, who once had aspirations to becoming an organized crime boss, is now thinking about turning into an FBI informant. Unfortunately—he didn't think this through much—this causes most of the illegal and semi-legal folk in Nevada to want him (or pieces thereof) dead or alive.
Ryan Reynolds is a nice surprise, playing an FBI agent, away from his usual light-comedy character.