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. Chapter 3 covered over 30 domains, but in its final section it discusses those within Raveloft who brave the Mists.
The section Travelers in the Mists is a fun and inspiring look at some of the organisations and individuals from the lore of Ravenloft. Some I'm familiar with from Expedition to Castle Ravenloft, other I was vaguely familiar with from previous source books, and still others were new to me (and possibly new to the world, for all I know). What this section provides most of all, though, are "sketches" of NPCs and story ideas to add to your Ravenloft campaign.
None of the ideas in this section are described in detail, which I think is appropriate in some cases and not ideal in others, but I imagine which is which depends on what you're most comfortable improvising. For instance, prompting me to create a secret society dedicated to taking down Strahd is pretty easy for me, but it's pointless to ask me to invent a clever but coherent mystery to stump a super detective.
Still other elements look far too abbreviated to me, but probably only because I happen to know the lore from previous source books. For instance, the exploits and studies of Gennifer and Laurie Weathermay-Foxgrove is pretty extensive. They literally wrote the book on the Mists and its curious properties, and it's so insightful that Van Richten forbade them from publishing it ("what you are writing is dangerous. It can only lead to sorrow, not only for you and your sister, Laurie, but for everyone that you hold dear.") Larisa Snowmane has a whole novel dedicated to her story, and here her riverboat becomes a convenient deus ex machina available for the DM who needs to rescue a party quickly. Obviously all of these stories (and many others) wouldn't fit here, and I think it's probably this book's hope that curious readers will hunt down old source books and novels to learn more. That's certainly the effect it's had on me. Whether you do or not, there are plenty of ideas in this section to add variety into your game.