This is an excellent book, it's just not a necessary book. That is, it contains some excellent writing. I consider myself to be a fan of both authors, and have read most of their work. That meant, I'd read everything in the book with the exception of an essay on writing fantasy by Emma Bull, and a previously unpublished early work by Will Shetterly. I actually really loved the new/old Shetterly story, even though it came with a disclaimer about how it's a rough, unoriginal, juvenile work. Stop apologizing, man! It's good! (It posits the invention of a device that stops time… but only within a finite bubble. The gadget is useful for preserving food, mementos, creating artwork… and possibly more sinister purposes.)
The bulk of the stories are from the Liavek shared-world series - and they worked better within the context of the original series. Go read them!
The book also includes the excellent novella Danceland, from the Bordertown, series, which I can't praise highly enough. Again, go read them!
Other than that, there's a story set in the world of Bull's "War for the Oaks," which appeared in the Diana Wynne Jones-edited 'Hidden Turnings,' and a Shetterly story which appeared in the Jane Yolen-edited 'Xanadu.'