If you shoot the enemy and they don't die immediately, they should at least become injured or shocked and attempt to seek cover.
At the moment they just do a massive pelvic thrust then kill you in one shot.
I shot a guy 4 times (one was in the face) and he calmly shot me dead then casually walked away like a T-1000
As it is now shooting the enemy is the equivalent of tapping them on the shoulder to let them know you're here.
It would also look more varied and realistic if the AI used ALL of the different stances that are available to the player. (extended lean, rolling while prone, etc...)