I read about half of it in detail over the weekend and found it to be (so far) the best product WotC has put out since at least RHoD. Great production, and very good maps. Not a fan of Delve format, but they do a better job than some in detailing the chapters as a story so you do not have to refer to the actual encounter details to get the story and plot elements. The stat blocks contain some small errors, and I wished that they included a larger overview map that exactly shows the relationship between the City and the Castle instead of a verbal description (although it does include a City map with a description of each district - including details for side quests - which is awesome). I instead relied on my Dungeon Magazine Greyhawk maps to get a better idea of the surroundings outside of the City. As said previously, the amount of Greyhawk lore - old and new (including paizo's adventure paths) - that have been either strongly or incidentally tied in is astounding, and quite fun. On a side note, if you own the 2nd edition version (which had awful maps), you could use those for the "filler" levels to add more to the dungeon "wilderness". It also makes a great precursor to Maure Castle, as the characters should be 12th-13th when done and have had some interaction with a group that is also involved with that adventure...
