Great City Lairs stands out because it is an unusually high value. The 0one Blueprints are all give you lots of gaming for little cash, but the Great City Lairs file is larger than your average blueprint. Unlike other 0one Blueprint files...which are usually about eight pages long, this file is a hefty 37 page product.
The maps are keyed to the Great City setting, but there is no reason you cannot use them anywhere...particularly when the Rule the Dungeon feature allows you to remove the text from the maps.
I am very happy with my purchase, and you will find that you cannot go wrong at this price. If you are a fan at all of the 0one Blueprints line, this product is completely worth your time at a cost/value ratio that is unmatched. I recommend it without reservation.