This is a fun little adventure, meant as a kind of Christmas-themed cap-off to Curse of Strahd. I recommend it if your group has just finished that adventure, and didn't play it too seriously. This is ultimately a light-hearted, fun, semi-comic romp that ends with Mordenkainen in the roll of Santa Claus, for instance. There are statblocks for the Krampus and Mari Lwyd, which might not make a ton of sense but then when was D&D ever shy about mixing and matching mythologies? My only nitpick is that the adventure often uses bold text to introduce characters even if it's not pointing you to the Monster Manual or an appendix. Furthermore, it uses monsters from Curse of Strahd (which, fair play) but the adventure doesn't call this out or make it clear which bold text references are to the MM or to COS.