Cage brings vigor and immorality to the role. He's actually good, especially in the scenes when he shows how he can be. The articles I've read (in Film Comment and Sight & Sound) cite that the film is humorous, and yes, it can be when Cage lets loose what IMDB calls a "hysterical laugh." Anyways, Cage's Terence McDonagh is stumbling through his lieutenantship as he goes to drastic measures to get to Xzibit's Big Fate, who is the main suspect in a case involving a guy who did some drug selling and his family. McDonagh cannot do anything well, as he messes up with all of his leads, especially Denzel Whitaker's Daryl, who he loses sight of at a casino where he's trying to find his woman Frankie (Eva Mendes). He's incompetent, double-crossing, and altogether dishonorable. That should give you good enough of an idea of what you're getting into.
But then again, according to people I know, it's not nearly as "gritty" as the "Bad Lieutenant" of 1992, with Harvey Keitel as an awful, awful, awful person, who does despicable things. According to the coverage I've read like in (I think) Hollywood Reporter and Rolling Stone , it's very dissimilar in other ways. I just think I should put it out there, but I don't have an opinion to match, as I haven't seen the original. It's the white elephant in the room for most people. I just think this movie, shadowed or not by Abel Ferrara's movie, should be perhaps a little better done. The plot is low-rate for a movie like this, and while not completely underwhelming, at least without too much scope. It's Herzog, it's Cage, meaning it's combined madness. But then again, while not insubstantial (it is a pretty inflicting movie), not quite as much as you might desire (at least of Herzog). C+