Overall, a pretty good little adventure. The materials are well-designed and well-written, and the adventure is reasonably interesting for a one-session playthrough.
However, my main complaint is that the encounters are not very well-balanced. The two encounters with the elementals were very tough, and I had to tone them down for my group as we were playing them. The final boss fight, however, was trivially easy, and would have been over by the second round if I hadn't boosted the bad guys' hit points and attacks. Same with the hellhound fight. The bodyguard fight seemed right where it needed to be.
It's definitely worth the price, but be prepared to do some tweaking.