I like the grav tank, but the thing I find most interesting is the weapons. I see some lascannons, but is that a freaking heavy stubber? Are Space Marines so desperate they need to start bolting on trash-tier weapons to their new shiny tanks? Mockery aside I quite like it and can't wait to riddle one with bullet holes (Death to the False Emperor!).
On the point of rules and new stuff I managed to find a less-than-legit full leak of the Chaos, Imperium 1 and Imperium 2 Index books. I haven't had a good look at the Imperium ones yet (other than to prevent a good friend of mine from going into shock over the edition change by drip feeding him rules on his favourite models), but I've been digesting the Chaos one over the weekend. My "copy" is missing about 10 pages but from what I see there's not a lot of background - at least nothing like a "proper" codex. This was expected.
Secondly - Legions are gone. Kinda. There's the <LEGION> variable keyword but it's not HUGELY relevant outside a few exceptions. The only Legions that actually get some kind of rules or restrictions are the ones devoted to a particular god, even then the only difference between generic Chaos and World Eaters is they can take can take Berzerkers as troops, and Emperor's Children take Noise Marines.
Death Guard (as of the time of this post) consists entirely of the units from Dark Imperium, a handful of generic characters, Possessed, Spawn, cultists and all the CSM vehicles except for the Helldrake and Mauler/Forgefiend. They are the only legion to get their own psychic discipline (for now) and all of the Death-Guard specific characters have some kind of buff that only benefits DG. And they're pretty good!
Thousand Sons have similar limitations - they are entirely made up of the stuff that was released with "Wrath of Magnus" last year, with the addition of Cultists, Spawn, Sorcerers and the full range of Chaos vehicles. It also seems that apart from Rubric Marines (which have the <LEGION> keyword if taken as Elites) all the Thousand Sons units, including Tzaangor are locked in to the Thousand Sons keyword.
So what does this mean? Well according to some other forums (which shall remain nameless), this makes all Death Guard armies everywhere illegal and invalid and destined for another 4 year rotation on the shelves. I call bullshit on that. With the rules as they CURRENTLY are, there is nothing stopping me from saying "My army is Chaos" and then mixing legions within that army. I can still use Bikes, Terminators and Havocs I painted up as death guard last edition (if I had painted my models...), I just give them the Death Gblard Legion (yes you can make up your own) and call it a day. Do they have the same benefits as the "True" DG units? Well... no. But seriously did anyone expect the Traitor Legions supplement stuff to carry over?
I have a Thousand Sons army that has no Thousand Sons units in it. Am I disappointed? No actually, because I can use everything as Tzeentch, call them the "999 Sons" and paint my guys up the same colours as Thousand Sons and run them in the SAME ARMY as true Thousand Sons with little to no penalty. And the Icon of Flame is pretty neat for 10pts.
This brings me to the only real problem I have with this book. There's not a lot of Synergy. I guess there's SOME, but it doesn't feel as impactful as in AoS. That might just be the nature of Chaos as an army though, I've never felt that Chaos armies have had an "enhance your units" list building philosophy and has always been "Unit X is good at this, so make sure you bring unit Y to do stuff that X sucks at". I feel like there was a lot more room to play with the <LEGION> and <MARK> keywords that wasn't utilised, but hey this is our equivalent of the free PDF rules. More will come, I'm sure of it.