STALKER was just at Nvidia's "the way it's meant to be played" event in San Fran last week. Not sure if anyone here saw any of the coverage, but IGN did a decent job with it.
Posting it here cause they make a small comparison to HL2. Totally different games of course, as the not only are the gameplay mechanics designed differently, but the graphics and physics engines are totally different.
Anyway, just an update in case you're interested. Move if you want to stick this elsewhere.