I like the general thrust of the episode. It's creepy without being genuinely terrifying, it presents a good mystery for the characters to solve, and it's open to enough "jiggering" to personalize for your party of adventurers. For example, when I ran the first half of the adventure, I added an NPC who was a "childhood friend" of one of the PCs but ran away from home, and I set the adventure in the 1970s--bingo, customized for my group.
That said, a lot of what should be fairly obvious scenarios aren't addressed within the module. For example, suppose the Doctor tries telepathy on a human here. What happens? For spoilers' sake, I can't go further along this line of questioning, but there's a set of character statistics that should probably be included that aren't.
Also, there are two different introductions given on two different pages, and that's rather odd. At one point, the narrative directs the adventure into a particular room that's never been mentioned before, with no further explanation, a room that goes unmentioned on the maps, too. A QA play-through should have caught that.
I'm just having some trouble, as GM, finding my way through the adventure, even after two read-throughs on separate weeks. I'll have to do a third study session before I can confidently run the conclusion.
It's easily worth the money--yes, definitely buy it!!--but be prepared to spend more prep time than you're used to with a pre-fab module.
[4 of 5 Stars!]