Let's jump right in.
New edition of 40K, new style of Codex, and so a new cover layout. I like it, it's bolder than the Fantasy covers, and the artwork has a real punch to it. It's a shame it's been used previously (on the cover of Blood Gorgons) but it's a lovely piece of art (especially after the lacking covers of the Fantasy books).
The fonts nice, although I hope everyone gets their own variant. The headshot of the featured race is now missing from the spine, which is a nice parring down in favour of visual impact.
There's some heavy embossing on the cover, to the extent that it can be seen from the inside cover on my copy.
Inside the book falls into the traditional sections: Background, covering from the Heresy to the present; Bestiary, with all the units getting there own entry; Warger, with the weapons detailed; Colour Section, with 'Eavy Metal showing off; and the army list itself, aff finished off by the reference section and it's gatefold page.
I'm not going to go through section by section, as the points I have to make apply across the book as a whole.
At 105 pages the book is the same length as the last Chaos Codex, but shy of the 145 page monster that was its 2nd edition forebear. It's in full colour throughout, with lovely artwork taking up whole pages, or occasionally a double spread, and some really nice page borders and paragraph dividers.
Talking of art, there are very few pieces which I've seen before, which is good. The art in the bestiary takes its cues from the models, which is a bit disappointing, as previously it's always good to have seen a different take on an entry.
The original Traitor Legions get very little page space, with the Heresy covered in such a way to avoid spoilers for the Black Library series, and avoid continuity stuff ups. There's a double page spread with a paragraph or two on the nine Traitor Legions, but that's about it. The four Legions that pledged themselves to the big four gods do get a bit more space by dint of their special charcters, but not much. This is a shame, as GW could do with setting down at least a bit of the background of each Legion in one place. On the other hand it again leaves space for Black Library and Forge World to have their Heresy era fun, and gives more freedom to players. Even the 'Eavy Metal section has only a handful of models from the original Undividd chapters. Anyone wanting to know more about the Traitor Legions could look here as a starting point.
The background section splits its focus between the old Legions, and newer followers of Chaos, with pages on Renegades. including some example chapters and warbands. Boxed out fiction sections have gone, (EDIT - I tell a lie, there are, in fact two tiny, tiny bits of fiction, accompanying the Noise Marine and Defiler entries) although flavour quotes head bestiary entries and the like. The Chaos timeline runs to four pages, with events give a bit of detail, with a few cool titbits scattered across 10,000 years.
Time to move onto the army list and bestiary and get to the heart of the book.
The Bestiary section is as you'd expect. I'm going to leave the rules alone for now, as I can't talk about them from any sort of experienced standpoint. There are some entries sadly missing. Mainly Daemons, as while they can be allied to the CSM force, it's disappointing not to see a generic entry to allow the likes Word Bearers and cultists of any stripe to have some occult fun in summoning them. I suppose you could count them as Possessed. The dreadnought has been replaced with the Hellbrute, as expected really. Chaos are still without a Codex droppod, with the Dreadclaw not getting a mention. Fortifications are also wholly missing. I guess Chaos will do as they always have done and add spikes to Imperial buildings. There are no new special characters added, but non have been lost either so that's good.
As things stand the only models that haven't got there own plastic sets are the Chosen, the Cultists, and the Hellbrute, but as they all come cheap in the Dark Vengeance set that isn't a huge issue, although as I'd like to covert these models so I don't have duplicates it's be nice to see them soon (rumours were saying the end of the month, but that talk seems to have died).
One thing it would have been nice to see would have been a page or two of Chaos conversions and Golden Daemon winners. It's always good to see other peoples models, but the Alpha Legion army doesn't count to my mind. Hopefully we'll see White Dwarf give Chaos a showcase next issue.
The army list see the return of two things that have been missing from Codices for a long while. Firstly there's the return of unique wargear to the Warhammer 40,000 universe, with six Chaos Artefacts in the armoury. Secondly there's the return of the old wargear lists that give characters and champions a huge run of items to go at. This is going to return list building to the days of flipping back and forth, but I for one am glad to see it back.
Otherwise the army list is pretty much business as usual, until the reference pages with the gatefold. I'd have rather see a separate card, but that's just me.
The biggest thing about the book is the feeling of freedom. Freedom from the restraints of the background and of the army list. There isn't even a "How to build an army section". I'm all in favour of this approach as it leaves it up to the player to decide how they want to do things, with those who want to stick to the backgrounds able to use the list (myself included) without prejudicing someone who wants a bit of everything.
Overall I like the book. It seems a good template for other Codex's to follow, and seems a step up from what has gone before, looking better even than the Warhammer Fantasy Army Books.The price tag still makes me wince a little, but (apart from not having a two pages for each of the Traitor Legions) I'm hard pressed to say it isn't a good book.
All that remains now is for me to write an army list and lay waste to the armies of the corpse god.