I've now completed two different sessions of this game within the past week. The parties took two different directions to the end, and both were so enjoyable to run.
I do have to disagree with the previous reviewer -- the CRs of the final encounter are definitely not lower than they should. If anything, they should be moved down a level or two. My first session was with 3 Level 7 characters. While they are a little stacked with magical items, the fight lasted 5 rounds and no one went down during the fight (though it was close). This also included some homebrew lair actions I ran.
The second session was with 3 Level 9 characters who weren't as stacked. Using the same CR 9 creature (and the same lair actions), I went max HP -- and it was still over in 5 rounds. Granted, one player charmed the goose in the 2nd round and it took the goose out of the fight for three rounds of attacks, so that helped. It also helped that the players' Nat20 attacks were a lot more frequent than any DM would want, but it did make for a fun evening.
Both adventures were over in less than 3 hours. The second was only 2 hours, but they also skipped one encounter. Overall, the players had a lot of fun. I'm definitely keeping this in my list for those short-notice games, as the prep time is minimal and the adventure is easy enough to run that it won't stress the DM too much.