For single player i'd also prefer if they went to something more non-linear, with more depth, more customisability and more "weight" to it. JK meets Deus Ex if you will.
And less acrobatics and flipkicks can only be a good thing. After all, everyone now knows that the matrix sucked and thankfully all the matrix sigs are long gone..
For MP: Some form of stamina bar would be nice.. a MotS meets Battlefield setup with more "realism" to it. Stamina bars that reduce when you do too much jumping.. accuracy crosshairs that reduce when you run or jump, but improve when you raise your weapon or crouch. All that jazz..
I still thinkthat instead of a health bar they should have a "halo style" blocking bar.. that reduces as you make blocks and increases when you rest.
Block > Quick attack. Quick attack > Heavy attack. Heavy attack > Block.
Any successful hit reduces their block bar. When its depleted then one or two hits kills.