This adventure is great fun. There's a bunch of roleplaying heavy stuff at the beginning (the PCs have to infiltrate an armed camp disguised as circus performers in order to secure access to the passage into the underdark) that has huge potential for hilarious fun (ask me about the orcish bard and his druid wildshaped into a giant ape friend's physical comedy sometime), followed up by some interesting enough combat encounters once you actually make it underground. I've played this three times (once as a DM) and the one thing I really noticed is that it plays out pretty different for a higher level party than it did for a lower level one. The presence of 4th level spells really switches things up in some cases here (Banishment in particular), so DMs should be prepared for what the party can actually do.
[4 of 5 Stars!]