I'm so used of facing brainless enemies in the likes of COD and Far Cry that I've been caught off-guard so many times in this game already - the AI is on another level here and one mission I was facing a guy in cover and another one on the level below who didn't have a clear shot at me but managed to bounce a grenade off the wall which almost landed at my feet. I tried running to cover but was killed by another enemy who was slowly flanking without me even knowing on the stairs the other side. When I tried it again, it played out completely different. There are no grenade indicators either plastered all over the screen so you have to use your eyes and ears during these frantic battles. Call of Duty is literally duck behind cover, shoot, duck, reload, duck when grenade icon appears and if you go off-rails ahead of the game intends then you just fall to the floor dead without even being shot. Harder difficulties in those type of games doesn't mean better AI either - it means more damage dealt and you get 'shot' more.
It's just mind-blowing to see what happens in each encounter and the sad thing is this game being 16 years old and we've become so used of shoddy AI, phantom bullets, vision cones/alert bars and generally dumb AI that's an insult to the word 'intelligence'.