Actually, it is an homage to a classic among D&D adventures, B2: The Caves of Chaos. Similarly to that venerable work, this product presents a canyon full of interconnecting, twisted caverns inhabited by a variety of evil creatures. The included material offers some speculative thoughts to kickstart your imagination, including several tribes of evil humanoids and some truly different encounters, but ultimately, it is up to you how you choose to fill out your lairs.
The main thing is, this product can save you several hours of tedious mapping and let you get right to the good parts of adventure design. It's also handy if your adventurers go off on a tangent one night and you need a quickie adventure to spring on them. Simply print these maps ahead of time and you can use them individually or as a whole. Though most of the caverns are interconnected, it's easy enough to close off a corridor here or there, leaving an isolated cave perfect for some horrible beastie to call a lair.
As is always the case with 0one Games, the work is high quality and very customizable. I own very nearly the complete series of Blueprints and I've found them to be not only quite useful, but very helpful in sparking adventure ideas. I had some thoughts of my own about how to fill it out when I purchased this product, but reading through the suggestions, I was so enamored by some of the ideas that 0one presented, I swapped much of what I had in mind for their suggestions!
Oh, and I should mention that I'm using this product in my 4E D&D games, and it works every bit as well and under the 3.5, 3E, 2E, or 1E rules. It should function equally well with GURPS, Fantasy Hero, TWERPS, or what-have-you.
[5 of 5 Stars!]