So I was reading some stuff about this game. It sounds like it's going to be fucking awesome.
Things I have read that are supposed to be in the game:
New, updated physics engine - supposed to take momentum into account more with your "freerunning"
Changing weather patterns with rain, snow, clouds, etc
Updated combat - no more wait, counter-kill, dodge, counter-kill, repeat, repeat
Ability to climb trees/rocks
Dual wielding weapons and the addition of a bow and arrow
Supposedly able to jump through windows INTO houses
Supposedly up to hundreds of enemies on screen at once