This is a great high-horror supplement that is packed with content that will slot perfectly into a developed campaign or could form the basis for excellent riffing. The authors clearly know what they're doing, and the supplement really shows off their cumulative experience leading original adventures in D&D.
I love the orver-arching theme here ("he hunts" in a quiet and mysterious valley -- definitely Ravenloft-esque vibe), and the general non-linear open-world approach that should allow DMs to really make this adventure come alive on their own terms.
I'm particularly impressed by the way the content is fleshed out as a lot of adventure supplements, including those written by Wizards, cut corners in both lore and storytelling. This gives a very detailed overview of the area, gives detailed descriptions of the main towns and various locations within them (including rumor blocks), a superb series of dynamic encounters, and what looks to me like a truly epic finale.
Finally, it's worth mentioning that the fit and finish is also wonderful. They've packed this with evocative artwork, pre-written narrative, battle maps, original stat blocks, and a clear mechanic for "ramifications" that decisions made in this part of the adventure will have for the next release in their series. All in all, impressive stuff, in my opinion, and I hope to run this some time, and I can't wait to see what else C&T have up their raglan sleeves.