I've watched a few full playthroughs on Youtube of it, one as Empire and another as Vampire Counts, plus several shorter ones as the others, and I wish I had the Pc + money to get it, but alas I am a wee bit limited at the moment.
Anyways, they've recently announced the new dlc, which is Beastmen. They will be on the main campaign map (with the two legendary lords actually having different starting positions), and they will be horde armies (like Chaos Warriors), meaning that you'll be razing cities as opposed to building towns by your own.
They have access to "beast-paths", which are similar to the underground movement of greenskins and dwarfs, but with a new battleground aesthetic. They also have a similar mechanic to greenskins in that they summon an allied NPC-army if they fight enough. Additionally, they have a unique ability in that their standard movement stance allows them to ambush other armies.
The DLC features two new lores of magic, the lore of beasts, and the lore of the wilds, the latter of which is unique to the beastmen.
Lastly, there's a new mini-campaign for the beastmen fighting against middenheim, mostly.