Well, let me touch base on a couple of things.
This book is set in the Scarred Lands, rather than a Scarred Lands sourcebook - that is, it is closer to Relics & Rituals than it is to Burok Torn.
I firmly believe that prestige classes are best used to help define and expand a campaign setting; I hate "generic" prestige classes. It is my belief that one of the best ways to help PCs feel a part of any campaign setting is by establishing clear ways in which their classes have influenced that setting. Wizards learn their magic from one another - this is going to lead to the development of entire traditions of magic, who share more than spells, but superstitions, secret handshakes and the like. If sorcery is passed on through the blood, then it makes sense that there should be "witch families" and eldritch bloodlines. Bards carry on the musical traditions of an entire culture.
These are the kinds of things that we are interested in exploring, and since we aren't willing to do that in a "generic" sense, we are going to do it for the Scarred Lands.
So, yes, there is quite a bit of Scarred Lands lore here; but it is also an excellent example of how a campaign setting is shaped by the various classes in its history. Just scratch off some of the serial numbers and change some proper nouns and you have a book full of useful resources.
And our Piratecat is writing the Sorcerers section of this book.