Oh, boy! Do I have some good memories of this module or what?
The upper level makes little sense as a building, but it was chock full of suspense. My players was way ahead of me when I DM'ed it, so they started to feel it was a bit easy. Then they got down and met the insectoids and were so sure of themself that one of them got killed! They were so cautious after that they never dared confront the orcs! I had them here some drums and that scared them blue!
What memories...
The follow up modules were just as fun. I think they were just as developed as they needed to be, and leaved lots of space for my personal inventions.