The stalker AI is pretty freakin impressive, they kick my ass a lot. I need a ton of stasis to beat them. Of course in a pinch I can at least drop them with a flying ripper blade lol.
I wicked like them too. They are honestly scary. Very few things in any games are actually scary. I start hearing that clicking/chirping noise they make and I get a bit of a sweat going. Their fights are even more horror than action.
I love their twitchy, almost insect-like movements.
I always liked how ANGRY they sounded when you did something to upset them (going into an area where they can't get you) or they charged you. You'd be doing something and this terrible hate-filled wailing scream would just rip over the headphones and it'd be like... "GAAAAH. I'M SO SORRY OH GOD."