The strike game has been reworked, so quick strikes like jabs are far more important and damaging and combinations can be a key to hurting your opponent.
You can whip knee to the body! Also, you can get leg kick TKOs.
The cage wall is far more important this year because it can be used to set up your opponent for submissions and you can wall walk from a seated position to get back to standing.
You can actually avoid getting your face pummeled if you're in the down position with your opponent inside your guard. You'll be able to dodge and weave your head to avoid strikes and to position yourself for a strike from the bottom.
Scarily enough, legs can break if they get checked - maybe a bit too real here?