A solid, non-linear dungeon. It has its ghost-related motive, some cultists thrown into the mix. My favorite element in the dungeon is probably a gelatinous cube which has two smaller gelatinous cubes inside of it; I'm a sucker for creative usage of commonly known monsters.
Overall, useful if placed on a map of a sandbox map. I wouldn't use it as a one-shot, though; the PCs are motivated mostly by their curiosity and greed (which is a good thing. Just not as a one-shot, IMHO).