I came across news of this sourcebook in a discussion over at The Piazza. From what I understand, this book is aimed at new fans who want to learn about Greyhawk, though it is definitely also a very useful reference for older fans. I personally love that both Arn and Blackmoor are used to reference the region so that people who have learned about Arn from the DMG will be able to find their way to the works of Dave Arneson.
It is also great seeing so many people across the fandom having helped contribute to the book. I am not a hard core Greyhawk fan, but it is always wonderful to see the amazing maps of Anna Meyer along with many familiar names on the list of contributors for art, writing and other aspects. Seeing my good friend David "Big Mac" Shepheard (From The Piazza!) having written a Spelljammer related section for Greyspace was also very nice.
This is not a sponsored review. The PDF is free from the DM's Guild. My blog has always been and will remain a non-commercial, non profit fan undertaking. I do appreciate feedback and comments though. Have you downloaded this sourcebook yet? If not, I recommend you check it out. And let me know what you think! :)
More discussion of this article at The Comeback Inn,
-Havard