Rise of the Governor follows a group of men through an ongoing zombie apocalypse. The story starts just after the infection begins, when there still is television, and ends shortly after they find Woodbury. One of the men eventually becomes the Governor.
In The Walking Dead, the Governor is a wonderful villain. He had to be cleaned up a bit for television, but even so he still exudes a sense of danger, a sense of teetering on the edge of a cliff. You never know what the Governor is going to do, but it's certain to be brutal. The Governor is bat-shit. I was a little hesitant to read Rise of the Governor. I was afraid the book would be a cheap knock-off of a great character, or worse, that it would humanize the character to the point that he isn't terrifying anymore. But, nope, he's still bat-shit.
Good books show its characters changing. In Rise of the Governor, all the characters change. Not one of the little group ends up who they started out to be. That's not to say that the book is flawless. It is written in present tense (he goes instead of he went) which I find annoying. Also it repeatedly repeated certain phrases--for instance, there has to be a better way of describing blood other than it being oily and black.
But the story is good. If you are a Walking Dead fan, either the television show or the comic book series, or if you love zombies, I recommend that you read Rise of the Governor.