It's very good, every bit as good as Paizo's Dungeon Magazine Maure adventures (which are by a different author), and also plotted like their adventure paths. The authors are top notch and all from Paizo even though it's a Wizards book. It is very much Erik Mona Greyhawk though, so if you like that, get the book. The maps, tricks, treasures, and challenges of the adventure are very much like Maure levels, so if you like those, get the book. And if you like the adventure path style of game play, the book should be right up your alley.
I don't know of anyone else really making as well designed dungeons as Mona right now. Me, personally, I don't care for the storyline stuff, but it is pretty interesting, reveals gobs of Greyhawk secrets, and should sell well.
If you buy it direct from Paizo you can get a signed copy from the 3 authors too (like I did).