Despite some (IMHO) overly gruesome descriptions, and also despite its obvious ripping off of Stephen King's The Stand
in many ways, I ended up enjoying this more than I had expected.
One terribly picky detail - in a late part of the book, there's a bit about a horse affectionately biting a person's hand. AFAIK, that's totally wrong. The mechanics of a horse's jaw makes it so that once they have something in their mouth, they have to bite down until their mouth is almost closed before it will re-open. So they might "nibble" at clothing, or even skin, with the teeth just a tiny way apart, but if they open their mouth widely enough to take in a finger and then close down on it, that's going to HURT (and possibly result in amputation of the finger.) Plus, there seems to be remarkably little difficulty in feeding said horse, despite there being no grass for the critter to forage and one would assume little or no hay remaining 10 yrs after the holocaust. McCammon just doesn't deal with these issues -- I suspect the horse was a convenient fix for the transportation problem and he didn't think enough people would object to those pesky details to waste time figuring out a work-around.