(Review also posted on my Goodreads profile here.)
Very slight spoilers for the mechanism of zombification in this review follow; it's nothing you won't learn in the first 50 pages or so.
I just looked at the date I started this book and realized that it took me 8 days to read this. It's a 600-page paperback, and I think the reason it took so long is just the sheer amount of information in it.
Obviously, the author did her homework. The world is well thought-out, internally consistent, and very realistic. It is, I think, a totally accurate representation of how the United States would be after decades of dealing with the constant threat of zombies. While the politics seemed kind of dumbed-down for this world, the military response, the characterization of the CDC, and the infrastructure of the world seemed solid. The zombies were adequately creepy with their fright factor enhanced by the fact that, basically, anybody who dies is going to become a zombie, so you are never really safe unless you are totally alone. That also led to interesting ramifications considering the death penalty and other political factors.
My problems with the novel lied in the characters. I found it difficult to take the protagonist and her companions seriously. Georgia, the main character, has a tendency to ramble on and repeat herself, even in the middle of action. At times, she would go on for a paragraph or two about what was going on, and then the text would continue, but I wasn't really thinking about that, because I was in the middle of a zombie attack, or something like that. Then why write it? The novel could have cut around 200 pages and not lost a thing. By the end of it, I still had little idea what any of the characters looked like, except that Georgia has brown eyes, and Buffy has blonde hair. And everyone, everyone, likes to talk a lot - in entire paragraphs at a time. If the characters were more lively, even if they rambled, this would've gotten another star.
The ending of this novel is a real gut-puncher. I stayed up a bit later than I normally would have just to finish it, and I have to say Mira Grant/Seanan MacGuire has some balls to do what she did in the end. It was really kind of great even if it was a total emotional roller-coaster. I just wish the previous 550 pages were as emotional and riveting as the last 50.