Overall this is a decently structured story and sufficiently succinct for a competent group of players to execute in one to two sessions. Keeping the story contained to a single location/structure is a wonderful concept that more writers should do. This allows DM's to incorporate a story such as this into their campaigns with little to no effort.
Overall the story flows well enough, though I believe the ending is in dire need of a rewrite, and would not recommend executing this story without changing the ending. In short, one of possible outcomes results in the players having an all-out battle to the death between one another until a final victor is found, only to have the party all magically aliveat the end with the "it was just a dream" ending.
In fact, one of the NPCs says this almost verbatim. Literally, the most hated cliché in all of literature is, "...and it was all just a dream". And here it is, in all its horrid glory.
Overall, I feel the book would have been better served if it had been structured more akin to a traditional play, starting with the dramatis personae, then moving to the setting description, then dividing the story into 3 separate acts. As I read through it, I found myself flipping back and forth trying to find out who the characters were initially, then trying to keep moving with the story, then trying to follow the progression.
The random encounter tables are good, and throwing a few fights into the mix is enough of a challenge to keep the players on their toes. A musical transition between the "phases" of the inn is a nice note, ala Silent Hill.
The chambers feel a bit punitive in nature, as each are effectively designed to cater to a specific class (cleric, fighter, wizard, thief), leaving, for the most part, the rest of the party to sit around and twiddle their thumbs. And, of course, if that the party does not have such a member, then the DM needs to partially or completely redesign the entire encounter, which is another headache. Additionally, if the party member dies in that encounter, there will be no one else to complete the task, effectively resulting in a TPK, unless the DM fudges the encounter on the next go-around.
In conclusion, I'd say this is a decent buy for the money, but not something most people could/would/should play as-is. Any DM that picks this up should plan on rewriting the ending, adjusting the challenge chambers to match the party compositions, and probably tailor the NPC cast (it's probably bigger than what is necessary).
[2 of 5 Stars!]