From the back cover:
As adventurers you may think you have seen everything: certainly your skills have brought you through unimaginable dangers. But now you suddenly find yourself in a place unlike any through which you have travelled: astounding, dangerous, and even amusing things confront you as you journey, both indoors and outdoors, through the unique and wondrous realm of Dungeonland.
This module was first conceived by E. Gary Gygax as part of the Greyhawk Castle dungeon complex and has been the source of challenge and fun for many skilled players of Advanced Dungeons & Dragons(R) game. It is finally available to all players and can be added to your existing campaign with ease.
Dungeonland is also designed so that it may be used along with its soon-to-be-released companion scenario, Dungeon Module EX2, The Land Beyond the Magic Mirror. Still, Dungeonland may easily be played on its own, and should offer hours of excitement in its strange landscape!