What, I gotta plug my own stuff? Grumble grumble...
Seriously, the book is pretty neat, even for homebrewers or other campaign settings. The Scion feats Nightfall mentions are essentially great ways to customize "theme" sorcerers, even if you don't use the titan-blooded folks from the Scarred Lands setting; for example, the Witch of the Old Blood feat can be used to create, for instance, sorcerers who derive their power from yuan-ti blood or the like, since it's all serpenty and witchy. There's examples for fire sorcerers, necromantic sorcerers (imagine being born haunted!), forge sorcerers — cool stuff. Stuff I'm myself pillaging for my own homebrew setting.
There are ways to customize spellbooks. There are sample sorcerous bloodlines, with copious detail (halfling sorcerers with the blood of the heavens!). There are ballads for bards to use (for example, The Epic of Carolann can be used to inspire courage, inspire greatness or inspire heroics, and with some tweaks in flavor text, could be customized to any game). There are discussions of how to treat sorcerers gaining powers from pacts with outsiders, and in-character discussions of how the "fire and forget" magic system works in the sense of the game itself. There are cool mechanics, yeah, but there's also a lot of exploration as to how these magic-slinging classes might fit into a world.
And there's a table of 100 random books you can find in a wizard's library, from their subject matter to the amount of worth they add to your own library, and it was a complicated affair to write, so buy the book!
Ahem. Please.