I've only had time to play for an hour or 2 so I can't comment on how immersive the game is but I agree this is not SS2 or even DE.
SS2 is still my all time fav. game! DE I never got into for some reason maybe SS2 was to fresh in memory.
STALKER has potential but for some reason the character models really bug me ...not enough to affect my enjoyment of the game but at the moment it's the only minor annoyance. Once I really start playing maybe I'll spot more bugs to make me re-think my position.