So, I've had a once-through on the Khorne Daemonkin book. Some initial thoughts:
The book itself is well put together, with lots of nice photos and pieces of artwork, some recycled but some new. Still in the ork-organized 7th ed horrid layout. Army special rules on page 110, after all the units? Really now. The flipping required building a list is insane. I plan to copy some of the detachment and cost pages to avoid the madness.
As the name implies, this is a book about Khorne, and includes not only chaos marines but daemons as well, all Khorne-flavored. Everything is either a daemon of Khorne or has the Mark of Khorne built-in or is something that neither would apply to (for example a Rhino). If you're looking for a fairly interesting way to mix in Khorne CSM and Khorne Daemons, this may be for you.