I gave this 5/5 stars. Don't let the cover fool you, this is a very profesionally made product inside, and hard to believe it was produced so many decades ago. It is very easy to read and very playable.
It is a series of mini-dungeons (even though some of them are pretty large) and each one has the hook of a treasure map that leads players to the adventure. They can easily be thrown into any campaign, in fact they don't even state what character levels are recommended for them. Almost any characters can manage them, but low-level parties would have to make very careful decisions. I have run them all with my players over the years, and they loved them. These adventures have a sort of "authentic" feel to them that is hard to describe.
But remember that this was written for 1st edition D&D. If you play one of the more modern versions you will have to convert it, but that shouldn't be very difficult.