The 3.5 edition (rules adopted by Pathfinder) version of the iconic Castle Ravenloft adventure, this book includes materials to make a fairly long campaign for mid to high level players. A good portion of the book is devoted to the maps and layout of encounters and Castle Ravenloft in particular, so there isn't as much Ravenloft information and lore as I would have liked (which is fair enough as this isn't necessarily a campaign setting). It does provide variations on how to run with adventure, with other materials being npcs, towns, events etc. It's what one would expect to see in any pre-made adventure, but larger.

What I do enjoy is that Expedition here varies in some content from the 5e edition, Curse of Strahd. NPC's in both also have some differences. If you don't mind converting, you can merge the material from both editions to expand the total adventure. Running Curse right now, I'm feeding material in and I can say that I feel there are certain things that Expedition does better. The story and material surrounding Donivich and Doru is much more interesting in Expedition, and NPCs like Kavan the Grim or Madame Eva have altered roles or motivations. I kept Curse's Madame Eva but brought in Expedition's Kavan, as well as an encounter at a locale in Expedition that was empty in Curse. They merge well.

For anyone looking to run Ravenloft, I would also recommend reading a few of the books, especially [I, Strahd] by P. N. Elrod to get a better feel for the lore and history, even if it's non-canon. I found setting lore lacking in the adventures alone. Knowing more of Strahd's perspective on his own history (canon or not) also helps to add more dimension to his actions and motivations in my opinion. ( )