Ran this for Free RPG day with the party consisting of all the pregens this scenario comes with.
First off, I enter all the NPC bad guys into Hero Lab to make things easier on myself. Hero Lab encountered validation errors with most of them as they were depicted, which was a little frustrating, but not a dealbreaker.
The story was alright enough: a murder mystery turns into a hell taking over the world scenario. The sheer gruesomeness of the murders and the trap scenario were interesting enough, but this was tarnished by the gameplay.
Repeating the ambush was not fun, quite frankly, and I ultimately ended up letting letting the party track our high-flying gargoyle with a perception check to keep things moving.
The broken shrine fight used up most of the party's resources, but caused some frustration as the rogue and ranger could not break the DR10 on the gargoyle.
In the catacombs, the party managed to not get deleveled by the wights, thankfully, but it's still not a very cool move with an impending fight against DR10 creatures.
The fight against the Shax cleric was actually pretty alright, the wizard greased the shrine (which was assumed to have candles), which made for a satisfying beginning to an enjoyable fight.
Then the Succubus came into play. The party was not fooled by her ruse, but she did get off her demon, which dropped the paladin, the cleric had used her last channels in the last fight, and the Fighter was Dominated by "the beauty he must prrrrrroteeeeeeect", and killing the wizard. With the standing party members being unable to break the DR, the fight was a slaughter that ended in a very frustrating TPK.
The worst of it was that the pregen ranger and rogue pretty much got the shaft at every turn, as they had no means to break anyone's DR.
Why this was picked for free RPG day I have no clue, as introducing new players to the game with unfun damage reduction fights using ill-equipped and underpowered pregens is not a good way to bring new players in. My players did not enjoy this at all, and as a GM I found this to be frustrating.
In theory, I kinda liked it, but in practice, this is a meat grinder with a mediocre story tacked on.
Scenario is below average for plot, and doesn't do a very good job of conveying to the party why they are doing what they are doing and what it's effects are.
The scenario makes up for this with great scenery description, very intimidating traps (I pretended the rockslide trap was a save or die and only revealed the ledge after the party looked over the edge of the cliff), and some good, but challenging combat.
The scenario also does a good job of promoting interfaction conflict, with a couple missions having a "get caught and fail" component, and some others being outright suicidal. There's also some room for DM creativity, and you'll need to use it as there is some vague stuff to be had. It was fun watching the players screw each other over for once (albeit accidentally).
The scenario could have benefited from a less useless end guy: I spent the monologue hoping the party would shoot him mid-speech, and the combat watching him get rolled. Meanwhile, the scenario never truly conveys why he is actually relevant.
In all, fun scenario: I would definitely run it again.