This is a big, though unfortunately somewhat uneven megadungeon adventure. Many elements work quite well, but other sections fall flat.
The strength of this adventure is the use of Lovecraftian horror which adds a ton of character to what could otherwise feel like a generic megadungeon. The best section of the dungeon is a large open cavern with several competing factions for the players to interact with. However, this is the only part of the dungeon that feels like a real, dynamic place. Notably, the final (and largest) section of the dungeon comes off as a "fun house" which has no rhyme or reason other than providing challenges for the players to overcome on their way to fight the big bad. The lack of good overviews for the adventure or sections further makes it feel like this is just a bunch of rooms for players to explore with no larger plot or purpose behind it.
The production values are decent for a third party publication. In particular, the art is excellent. However, like many third party products it often reads like a first draft manuscript that no one ever got around to reviewing or editing.
All in all this is a mixed bag, but it is well worth the $10. I'd give it 3.5 stars, but will add a bonus half star because this may be the first work in the English language with express references to both H.P. Lovecraft and West Side Story.