The biggest problem I’ve seen is that so many of the rooms are very small, making for cramped, awkward maps. Sometimes our group calls it Abomination Closets, it’s so cramped.
I’ve seen suggestions that you double the size of all maps but I’m too lazy for that.
Other than that, I have very few complaints. It’s reasonably well-written and the difficulty tuning is good, assuming a party of 4 at the correct level.