There's very little reason this should work.
Ed Brubaker and Greg Rucka want you to sit down, pick this up and become captivated by the stories of the Gotham City Police Department. A force that has become all but neutered by the exploits of The Dark Knight. Honestly, who wants the cops to come save you when Batman is on the prowl?
It had to be tough to try and write this without the reader asking the question, "Why not just flip the switch and let the bat-signal flood the sky?" The answer: this is their job, not his. The GCPD struggle with the fact that they're always overshadowed by The Caped Crusader and that they have a lot of resentment deep in their system. In fact, that's basically the subject of the first arc, In The Line of Duty.
Detective Lewis needs to capture Mr. Freeze following the brutal murder of his partner, Charlie Fields. Feeling guilt over Charlie's death, Lewis wants just this one victory without the help of Batman and refuses to let the beacon shine.
In The Line of Duty is important in establishing just why you should care about these people. It gets the reader right down to their level, sympathizing with their feelings of inadequacy in relation to Batman. After that connection is established, Rucka and Brubaker get the wheels going with some top-notch stuff.
The two arcs that follow are gripping stories, especially Half A Life. They do a good job setting the tone of where this series intends to go throwing red herrings all over the place, keeping the reader guessing until the big reveal.
This is the perfect example of why people should never write off comics as a storytelling medium. Even if you're not a fan of the superhero genre, this is a series that can fit snug on the bookshelf of any crime fiction aficionado.