This gets two stars because it evoked in me enough curiosity about what was going on to persist to the end. But it certainly left me not ever wanting to read another book by the author.
For one, the prose is cringe-worthy. It uses epithets like "the beautiful raven-haired informant" rather than use the name of the character; it has intrusive speech tags like "groused" and uses punctuation like "!?" at the end of sentences. It indicates someone is Hispanic by spelling sentences like: Das allcha gonna haf? It ends on a maudlin cliche--more than one really.
But the reason I find it a pretty lousy novel lies at the heart of the plot. It's what's known as an "idiot plot" in terms of critiquing because it only works if the characters are idiots. In the case of the villains, as in so many "gritty" and "hard-boiled" detective fiction, they would have been free and clear if only they hadn't hung a "look-this-way" sign by doing things like persecuting the hero and machine gunning his home. In the case of the hero, Shane Scully, instead of going rogue, it would have made much more sense when opposed by corruption at the top of city government to either go to reporters--or, here's a notion--the Feds. It's rather what the Federal Bureau of Investigation and US Attorney is for, and a cop would know that.
