My players and I really enjoyed this adventure even though we're not very big on roleplay heavy games. We are however big horror movie buffs, and The Waystop hit all the right notes for us. It highlights some popular tropes, and subverts them later to excellent effect, and we had fun trying to figure out which movies inspired the scenes (we thought of The Sixth Sense and the Shining).
Initially, I had some reservations about how open ended the narrative was, but everything went smoothly once the players and NPCs started actively interacting. My players were pretty suspicious about the NPCs (they thought the NPCs were ghosts), so they stuck with each other the whole time and refused to go to sleep, then started panicking when Part 2 began because they'd used some spell slots earlier and had not recovered them.
This is going to be my go-to horror adventure for Halloween from now on. I'll also be using The Waystop whenever I need to whisk players off to Barovia for Curse of Strahd. The adventure is practically made for it.
[5 of 5 Stars!]