It's a grab-bag, trying to cover five different monster types, and do so with a limited word count. And then it adds some new mechanics and bits on top of that. But is it good? Depends on what you want.
We start with Prometheans, and it's decent enough. Given the rarity (and uniqueness) of the "Created", there aren't any dedicated groups focused around them, which makes sense. We then get a lot of material on how the existing compacts try to view Created, and what tools and records the Conspiracies have. Actually, a lot of it is more how -Prometheans- see these groups, rather than the other way around. And the tools are more "generic" in their usefulness, rather than specific to fighting Tammuz and Golems. There's also some sample Created, using HtV mechanics, along with story hooks and ideas for how to handle things at different tiers. Probably one of the best chapters of the book to be honest.
Next up is a chapter on Changelings that... I'll be blunt, the rest of the chapters on monsters are actually pretty worthless. There's some good bits and pieces to be sure, but they're all rather uninspired, brief, and largely redundant. To some extent I blame this on two factors: first is that this book is trying to replace the need for relevant works (i.e. you can use the chapter on Mummies, rather than buying Mummy: the Curse), which will make things redundant to people who already have the relevant (and more developed) books; the second is the limited word count. Each of the entries (Prometheans, Changelings, Geists, Arisen, Demons) could get their own book potentially, much as vampires mages and serial killers already did. Heck, a two-part series where each faction got twice the page count could've helped.
Some things I'd have liked to have seen....
Changelings - A compact or Conspiracy could've been interesting. A group of people who investigate strange cases of abductions-and-returns, possibly backed by Privateers or Loyalists, could work nicely. Also, some guidelines on how Hunters would actually interact with these creatures (what does the Cheiron Group actually know about Fae containment, or how does the Long Night fight a Troll, for example).
Geist - I'll be honest, Sin-Eaters always struck me as a pumped up, specialized Hunter Conspiracy to begin with. I'd have liked more exploration of how the global Sin-Eater cell structure dealt with the assorted Compacts and Conspiracies. Because of all the different "monsters", Sin-Eaters seem to have the most social interactions with Hunter factions, and really feel like they should hammer home the idea that the C&C don't exist in a vacuum in regards to one another.
Arisen - I like the story hooks peppered throughout the text, and I find the idea of a Compact in Egypt to be interesting (if a bit too localized for my use). The Conspiracy in this chapter is also interesting (a group that eats monsters to gain supernatural powers), but I was left wondering how/why they got powers and the gourmets of the Ashwood Abbey didn't. I also found the side-paragraph discussing gender identification to be... unnecessary. Maybe it's because I'm enlightened in my indifference (i.e. I didn't find it jarring/exciting/aggravating), but it seems like the relevant NPC description could've been explained with a single sentence ("Jess chooses to present as neither male nor female." which is a quote from the sidebar, and sums it up nicely). I mention this because in a book already struggling with page count and content issues, it seems like wasted space that could be better spent elsewhere. Anyway, after reading this chapter I wasn't sure what mummies do beyond gather cults and magical relics and sleep.
Demon - Honestly, it wasn't bad. It does suffer from the problem of Demons in the world of Darkness being more akin to rogue programs escaping from Thomas Ligotti's word processor than anything with a basis in actual myth, while the Hunters just kind of go along with the discrepancy and just accept it all ("God isn't a white, bearded man on a throne. He's that gore-caked clockwork mechanism down in my basement. Duh!"). That said, I did enjoy the Utopia Now Compact: a group of anarcho-libertarian businessmen who seek to "lobotomize" demons and use them as a source of power for their dream of a new free state.
Wrapping up the book are new rules for new (and revised) Dread Powers, along with updated mechanics for use with new World of Darkness God-Machine update. Tactics and Practical Experience (now Practical beats) are reworked for the better, but honestly the GM update part should probably be part of a free download. Still no update on my main gripe though (namely, why you need to spend anything to learn how to drive a truck into a werewolf or pull out a vampire's fangs with a pair of pliers).
Anyway, in summation: the book ranges from bland to quite good, depending on what you want or need. But the more other books you own, the less useful this one becomes.