One review I read said that this film sees like it's trying to be a violent version of It's a Mad, Mad, Mad, Mad World (and that it was probably even pitched that way). I agree with said reviewer about how coll that would have been. Too bad that's not the case.
Here's the deal, I was entertained by this movie, and had fun watching it, but it's not really that good. The script is really undercooked, there's like maybe one character worth caring about, almost all of the characters are thinly developed caricatures, it takes too long for thigns get started, and, once they do, the results are underwhelming and disappointing. I didn't care much for the third act revelation/twist, but in a sick way I did find it darkly humorous (I'm talking bitter gallwos humor here)- which may have been the original intent. The editing got a little annoying (sometimes it's hard to tell what the hell is going on). The way things unfold is okay, but it's been handled better (see also Traffic and other films with intersecting storylines).
This all feels derivative of Ritchie and Tarantino, (or also Troy Duffy), which only bothers me when it's mishandled, as it is here. There are some things I liked though. I liked that there is an ensemble casdt and that Carnahan takes risks by showing that just because A-listers are present doesn't mean that they'll stick around for very long. There are a few really good moments with genuine surprises, and some just plain old good scenes period...they're just few and far between. Reynolds is probably the best, especially since his role is the most fleshed out. I really liked Chris Pine though- he just steals the show and really hams it up providing some memorable moments of whacked out funny/scary. Piven is also good at playing coked out.
As wild and nutty as this all is though, it's a real mess. It seems to be as coked out as Piven's character, but that doesn't really help much. The only real film where they kind of thing worked was Fear and Loathing in Las Vegas (and even that is hardly watchable-it's at least really good though).
I don't really recommend it, but if you do see it, don't expect it to be as great as it could have been.