Aim is sluggish, but so is the movement of the camera... I'm still not adjusted to it yet. The other issue is... You have to aim at a players upper chest to hit their head... Annoying mechanic. I've noticed this is becoming an issue with most games. You have to shoot their upper chest cavity in order to hit their heads. There is no, "head," shot... it's more like a, "upper chest/lower neck," shot...
I can look at it this way... In RL, they would be dead even if they didn't hit the head... but it wouldn't be a headshot!