Heh! I didn't notice you were actually one of the authors of the book, I'm embarassed
My doubts about the usefulness of this title are because of the description:
I thought that the Book of Vile Darkness already had "everything you need to know to play evil characters", and discussions on the nature of evil, different evils etc... since it's a general book, I wonder what else about this can CoR have? How is an evil character it different in FR compared to all the other settings? I can only think of the FR-specific evil organizations, but those were already well treated in Lords of Darkness.
From the description above the only "new" stuff seems to be the usual feats/spells/etc (well ok the planar touchstones are very new), of which I wonder how much is entirely new and how much is just revised.