The book is formatted such that the 60 some odd pages of the book detail ten classic horror monsters, and each monster has about six pages dedicated to it. There is a sidebar (for each) explaining what about the creature touches some primal fear in mankind, and/or perhaps the history of the monster in folklore and popular fiction. Each monster has an introduction, an ecology (or necrology for the undead), some known examples of the monster in the Golarion setting, some extra rules or options for customizing the monster with new feats, abilities or equipment, and a custom statblock and illustration of a single advanced version of the monster.
The format works very well to ensure that each creature gets enough treatment that you can do something with it; if gives you loads of ideas on how to integrate one into a campaign, and make it work.
Sadly, of course, the system is Pathfinder, which as a variant of D&D 3.5, is one that is in many ways poorly suited to horror gaming. Granted, a lot of that can be overcome with metagame considerations, but it was also clear from reading through these entries that they were struggling at times to work around the obvious, "the cleric easily turns this monster" or what-have-you. Because it's a particular interest of mine, horror roleplaying, even in systems like D&D (or Pathfinder, which I consider a variant of D&D, despite the name) is something that I've given a lot of thought to, and I think that it's a struggle to work against the system in many ways. That said, this book had some pretty good advice on how to make these monsters come "alive" in the campaign, and not just be disposible encounters, which is exactly the wrong thing to do if you want to retain any semblance of a horror vibe at all.
So, I give the book two thumbs up. It takes a difficult subject; making standard, classic, well-known and probably (honestly) overexposed monsters and making them horrible again, and does a pretty good job with it, in spite of a system that isn't really conducive to that particular role. So... good job, guys. The focus was more on using the existing rules instead of really "revisiting" them, i.e., providing more options that diverged more from the standard SRD rules for the creature as originally written, but that's OK. Although I would have liked to see the latter, maybe my desires there wouldn't be reasonable in relation to what the standard buyer of this book would probably want to have seen.
The monsters included are pretty much what you'd expect, with perhaps the exception of the first one, the derro, who's inclusion as "classic" is perhaps suspect (they referred to the infamous Shaver Mystery stuff from Astounding Stories in the 50s, as well as making a more difficult link between derro and the gray alien mass hysteria phenomena.) In order, the monsters are derro, flesh golems (i.e., Frankenstein's monster), gargoyles, ghosts, ghouls, hags (lots of wicked old witch folklore here), mummies, vampires, walking dead (skeletons and zombies) and werewolves.