A solid adventure that was a hell of a lot of fun to run for a group of friends. Was very beginning friendly as well!
For the Players:
The abilities you gain for each of the characters are unique and the new class archtypes that are within the adventure are really great and unique. Whole hearted would suggest bringing them to your DM and seeing about being able to run a character based off them. For those that maybe wanna remove the final human element that is Sha-Gi, the human monk, from the party, maybe see if the DM is cool with making him into a Firbolg instead.
For the DMs:
I would suggest though that if you're going to run this adventure, if you get to climactic final fight, perhaps make the final encounter immune to being stunned or maybe give him some minor Legendary Actions/Legendary Save. My party's Sha-gi ran right up to him and Stunning Fist him 3 rounds in a row, making it so Vell'mah could just riddle him with all the crossbow bolts.
Overall, this was a great 6 hours well spent with a lot of great and funny moments. The Fear mechanics are great and make it possible to have the adventure run without always having to rely on the players remain in the characters that they're clearly based on.