Free DLC with mongols is out now.
They seem like a very interesting civ, atleast for the warlords out there. +30% attack bonus vs. city-states and their units and +1 movement for horse units. Yes, this means that their horsemen move 5 tiles per turn. Not only that, but their Keshik Unique Unit is just as fast (normal knights only have 3 tiles per turn), gains experience at twice the rate, and generates great generals twice as quickly. Oh, speaking of which, their other unique unit, the Khan, a Great General replacement. Not only does it also have a movement of 5 freaking tiles per turn, but it also acts as a medic. Twice. Yes, it heals each unit next to it 2 hit points per turn and also has the speed to actually catch up with their hyper horsemen, and generates twice as fast in the medieval era, not to mention you can get one easily by simply picking Warrior Code down the Honor Social Policy tree.
I'm probably going to have some fun with them later on.
Edit: I just noticed. Keshiks are ranged. While this does change their tactics a bit, this might just make them more powerful, and far more better than the Camel Archer. Granted, Camel Archer has a 2 point stronger ranged attack. And that's it. Bar perhaps a slight advantage in melee combat the Keshik is superior in pretty much every way. Imagine moving up a Keshik to a city, firing, then retreating beyond city bombardment and pikeman retaliation, leaving room for another one to do the same, which can then be followed by as many Keshiks as you could fit there. Oh, and if they get close enough to actually attack one? By then they will probably be wounded from all your ranged attacks and the Keshiks may actually have a chance to survive. And if they do, they get healed up in a turn or two by their Khans.