I picked up Van Richten's Guide to Ravenloft and have been reading it cover to cover. This is my review of the book, chapter by chapter.
Ravenloft is a D&D setting named after a very particular castle just outside of a land called Barovia. You have to separate the name "Ravenloft" from "Castle Ravenloft" for this book to make sense. This isn't a source book just about Castle Ravenloft, or just about Barovia, but about all of the Domains of Dread.
There's a conceit that the book, and presumably its title, exists in-game. Maybe there's one of those Victorian-style subtitles that hasn't been revealed to us. Something like Being a Compleat and True Account of Van Richten's Guide to Ravenloft & the surrounding lands of mist, called the Domains of Dread.
Despite the potential confusion of what exactly this book is a guide to, it's particularly refreshing that the in-game flavour it employs are letters between Van Richten and the younger generation of monster hunters he calls family. Nowhere are there snarky and silly quips in the style of Volo's Guide or Xanathar's Guide or Tasha's Cauldron or Fizban's Treasury. You don't turn the page of this book to read more about the horrors that lie through the mist only to be highjacked by a margin note declaring that the mists of Ravenloft actually smell faintly of freshly baked apple pie.
The game characters here work with the book to keep you in the game. It's a minor thing, but I appreciate it.
You wouldn't think there'd be that much in an introduction, but actually there are a good 8 pages before you get to chapter 1. The first section introduces the setting, and somewhat clarifies that Ravenloft is a realm named after the infamous castle within it.
It does a lot to set the mood of the book, too, with in-world correspondence between Van Richten and his younger monster hunting pals. It does just as much to forewarn unwary readers that the book is likely to contain elements of horror, and to warn Dungeon Masters that you can't run a horror game for people expecting a "typical" D&D high fantasy game. Both are fair warnings. Broadly speaking, I'm a fan of horror, so these warnings are lost on me. They feel similar to people warning me about spicy food, not knowing that Carolina Reaper is where my spice-o-meter begins. But for many people, this is a good reminder that yes, a book about a dangerous vampire could be frightening, and that there's more to this book than just vampires. It's also a valuable reminder for a Dungeon Master whose threshold for horror may be extremely high that not everyone is as comfortable with the subject.
The introduction also presents the concept of Darklords to the reader. Each domain of dread has a Darklord, and in fact each domain revolves around its Darklord. In fact, a domain of dread literally exists only to imprison its Darklord.
Interestingly, the Darklord's importance to a domain doesn't necessarily reflect upon its challenge rating. The introduction specifically encourages the Dungeon Master to use a domain's Darklord throughout the adventure, and not to hide it away until the end. A Darklord's presence is meant to be felt.
The entities (or whatever) responsible for Ravenloft are especially fascinating. The book doesn't say definitively what they're meant to be, but provides a few appealing suggestions. This is the kind of metagame uncertainty I love. Potentially no two Dungeon Masters are going to have the same definition of who or what a Dark Power is, or what its goal is for crafting the realm of Ravenloft. It's not a mystery to the Dungeon Master, but it's left undefined enough to allow for serious customization.
I've glanced at the table of contents, I've read the back of the book, I've read the introduction, and I'm still not entirely sure what to expect. What I thought I was buying was a tour of Barovia, but that was admittedly naïve because Ravenloft of course is a larger setting than just one town. I'm ready for a tour of the realm, though, and because I'm a fan of horror, I suspect it'll be difficult for this book to disappoint.
Next chapter covers player options, and I'm really hoping for a Witch class.