Well, this was a five minute job, so none of the special rules have been filled out. They're exactly as they are in the Imperial Guard / Chaos Space Marine codecii.

The main trade-off occurring in this Codex is the loss of the Imperial Guard uniques, such as Commisars, Rough Riders, Ratlings, Ogryns, Storm Troopers and the specialised IG vehicles in favour of Daemons. Yes, I know Chaos Ogryns are a cool concept, but IMO completely unnecessary because of the presence of Daemons. Hardened Veterans and Storm Troopers were dropped in favour of Deathworld Veterans, as the WS of 4 suits Chaos much more than the BS of 4.