I love the Walking Dead graphic novel series. When I stumbled across this Rise of the Governor novel spin-off, I had high hopes based on previous experience.
RotG is a prequel of sorts to the graphic novel series, endeavoring to explain the secondary character Governor's ascent in Woodbury, and--more importantly--how he got to be such a sick twist. As the characters fight their way across the zombie-riddled South trying to find safety in an Atlanta refugee camp, we're initially treated to plenty of obvious jump scares and gratuitous gore. Splatter fans will probably be satisfied; I was just bored. But it gradually transitions from cheap zombie-horror to more-interesting survivor drama.
The ending has a fairly substantial twist that I don't want to give away. Unfortunately the authors work so hard at making sure the twist is shocking and unexpected, that when it finally happens it's not really believable. (Not if you're familiar with the graphic novels, at least...)
Overall, I'd call Rise of the Governor "adequate", somewhere between 2 and 3 stars. I have the followup novel "The Walking Dead: The Road to Woodbury" sitting upstairs in my reading pile, but I might be returning it to the library unread.