There is a purpose in watching this movie, and that is to check out Christian Bales's acting chops before his Batman Begins opens in the summer.
The narrative is confusing at first. There doesn't seem to be any clear direction on where the plot and its subplots lead to. All we know is Bale looks thin, for some reason, isn't getting enough sleep, and develops relationships with a widow, her kid, and a hooker.
As always, most dark thrillers have a twist at the end, and if you can sit tight, you'll get it - not that it will be presented in a confusing manner, just that the pacing could be improved. Actually with shows like Fight Club and Memento around, this show might feel like a fusion between the two, and hence, you might have warranted a guess on the twist midway through the show.
Christian Bale has sacrificed quite a bit to look the role. With the lingering full body shots of his aneroxic body, which at times is painful to look at, one can imagine the kind of toil it must have took.
Definite for fans of mysteries and thrillers.