I started reading this book knowing nothing of the premise beyond what it says on the book description, so I'll let you have the chance to do the same too - this is a great book, go read it, or at the very least download the Kindle sample and start reading to see if it's something you might like. Within its genre, it's excellent.

From now on, spoilers.

Zombie stories have one thing setting them apart from other classic monsters: it's virtually impossible to make the monsters likable, and to take their point of view. There will never be a zombie "Twilight", thank goodness. When something of the sort is attempted, it automatically strips the zombies of their zombieness (e.g., the movie Warm Bodies, or the nevertheless quite enjoyable Stubbs the Zombie video game). A zombie with agency is more vampire than zombie, really.
So it's quite an accomplishment for M. R. Carey to create a post-zombiecalyptic world in which one protagonist is still very much a zombie (they're not called zombies - true to the genre, they're not identified as such, although Carey's choice of phrase, "hungries", is annoyingly childish. The fact I read this right after "Uglies" didn't help either).
But the story calls for Melanie, said part-zombie, to become less and less zombie-like as the story progresses. At the same time, the full-fledged zombies themselves become less of a central threat to the group of survivors, and the story takes sort of a weird turn into something more reminiscent of Nolan's Planet of the Apes prequels than a zombie story.
I'm not saying this is necessarily bad. As is often the case with any good zombie story, the zombies themselves become a dull background for the transformations that take place in the living protagonists themselves, and this story certainly offers a new twist on this old tale.
That we are left pondering at the end just what kind of monster Melanie has become as she grew through this story makes this book's message much less spoon-fed than is often the case in the genre.

Carey has not written the perfect zombie book. Zombies as a topic seem to make that a very difficult thing to do indeed. But his book, with its strong but flawed characters (and such wonderful female characters that at first I thought M. R. was a female author), makes one of the best uses of the zombie mythos to date for telling us something about ourselves as humans.