I own both the orginal book and scan of this adventure. I have hand drawn the entire module on large scale hex paper over the last year, while Dungeon Mastering it for a group of five. I would say I have a very intimate knowledge of this monstrous adventure. Overall this is a must buy for anyone intrested in first edition D&D. Pair it with the World of Greyhawk Fantasy Setting. Some encounters, clues and goals are not directly connected to the next room key and adventure path. This is a HUGE module. A through reading and a few re-reading's with notes is recommeded during play. Dungeon level three, four and the Nodes of elemental Evil require extra preparation before play. This is a classic " killer / meat grinder " dungeon if not played very cautious by the player characters ! The ultimate 1e challenge. Feel free to send any questions to me about this adventure, twitter: @jamessnapguild.