I've not had much time to read this since I got it last week secondary to Historicon coming up. This is going to be a short review.
If you want to read a proper review look at MongooseMatt's review here: link
The handbook has a TON of stuff in it. It has four sections. One is on multiplayer games. This is pretty obvious stuff, how to set up games with multiple players, how to select sides and so forth.
It does have some battleplans for this so that is useful.
The next section is on narrative gaming. I kind of skimmed through that as we already do that. There were a couple of battleplans here along with forces that they used to play them, which is really helpful.
The one was pretty normal sized for a game, the other was a massive multi-player slugfest.
The campaign rules are next. This section looks great. First up are rules for Path To Glory campaigns. This is for more than just Chaos forces. The Path to Glory campaign includes rules for Stormcast, Death, Fyreslayers and Sylvaneth as well.
Having looked at it the Chaos stuff looks fairly complete for Khorne and Chaos undivided but for the other Chaos powers it is a little lax. The follower options are weak as they haven't fleshed those forces out enough yet.
For example if you are rolling on the table for a Nurgle warband you have 1 option for spawn, 1 option for warriors and 4 options for Putrid Blightkings.
Similarly for your champion followers the only option available to Tzeentch is a sorcerer lord and Slaanesh a lord of Slaanesh.
Khorne's table is well filled out though so if you want to run Khorne or Chaos undivided you are all set.
The rest of the campaign section details other types of campaigns that can be run.
Then there is the competitive play section. This I spent the least amount of time looking at.
Overall it looks like it could be useful for any fantasy wargamer. For, I think, $25 USD it is a pretty good buy.