For much of the volume, this could just as easily be post-nuclear, or post-plague. That's a compliment, because The Walking Dead isn't as much about the zombies as it is about how people survive and adapt. The survivors find love and lose people they care for, and nearly lose them. They find safe harbors that aren't really, and wind up back where they began. It's all very realistically done, and I ended up feeling attached to these people, flawed as they may be. But there are zombies after all. And they are frightening, gory, and everything that a good zombie should be. It can be hard to make a zombie scary. They're slow, unarmed, and dumb. The real horror, for me, is the thought of becoming like that, losing your mind entirely and going on and on (even completely frozen) unless somebody delivers a headshot. That is what's really scary to me. I mean, yes, eaten alive isn't exactly my retirement plan, but I think I'd rather that than to entirely lose myself. There is plenty of eating, though, and masses of zombies making surprise appearances. These zombies are very, very quiet.
The Walking Dead isn't just about scary zombies, or just about a band of survivors trying to negotiate a post-apocalyptic world. It's both, and it strikes a good balance between the two, and makes for a gripping read.