Recently incorporated this into my ongoing campaign.

The scenario ended up taking my PCs about 14 hours all told, maybe 17 if you include the surrounding campaign stuff, but I don't push my players for pace unless it's a combat or chase, and we're used to playing slow, investigative games. So they got to do a lot of snooping before finishing. If you ran this at speed, you could do it in about 6 hours.

The plot involves an escape artist and his murder-suicide, and it allows the players a good bit of leeway in how they conduct the investigation. The structure is quite open, and only gets better if you work on it, it's not one of those scenarios that essentially needs repair work before you even start.

I didn't act any of the main NPCs as eeeeeeeeeeeevil which played to the scenario's strengths. My players weren't thrown off by this, but it did create a good bit of uncertainty, which perhaps went on too long, even when they were solidly on the trail of what had actually happened. There are several great NPCs, as well as the usual raft of info-dispensing types, and even those often have some nice description and a solid background to enable you to create a character easily.

The locations were well thought-out. The maps are quite workmanlike and sufficient to the task, though my players kept on examining them with hawk eyes and constantly picking up on extraneous details that had no relevance, which was unfortunate, but again, not the fault of the scenario.

Even though I'm no stranger to improv, and I had to do some work integrating this scenario into my campaign, it still provides several avenues for scenes that went unused, and it caters to a range of outcomes. It is well-written throughout and has been thoroughly proofread. I noticed precisely one error, which is in the timeline long before the scenario starts, so it can be corrected by swapping out one number.

The cult in this scenario is unusual, and one of the best aspects, that I was happy to develop further when I ran it, were specific members and its activites. You can see that some thought has gone in to its design; this isn't just a cult murdering people and running rituals hoping to summon something unpleasant. The range of motivations available means you can even play some NPCs quite differently than usual, and establish some empathy, which made for a better scenario.

We didn't use the pre-gens, I slotted them in as NPCs to populate the scenario.

The main strength of this scenario is the amount of imagination it contains. There are multiple situations which, used correctly by the Keeper, could easily make this scenario something players will talk about for years. The scenario never pulls the awful trick of "Here's a place, have fun coming up with what to do and what it looks like, the only limit is your imagination!" which some otherwise-excellent scenarios deploy. The scenario gives you a lot of tools and suggestions and doesn't railroad you.

The background and lore specific to this scenario are new and interesting, I quite enjoyed dropping something new on my players, some of whom think they have seen it all. The handouts are really good. My only minor quibble with the supporting material is some of the NPC profiles are broken up by column/page breaks, which can make organising them a little more finicky, but this is a common thing.

Overall it's an excellent scenario that is also professionally organised and looks good, including some fantastic art that I dropped on my players ASAP. Lots of advice for the Keeper, but none of it particularly constraining.