First off, it looks quite spectacular, and I'm really amazed at how it runs on my junk rig, a E5200 and a 9800 GT with 4 gigs. In closed environments it's always around 50, and only when there's craptons of shooting and effects it goes to around 30-25. High settings on 1280x1024, too.
 
However, some things were a tad off. The shooting feels odd in some moments but just right in others. The human enemies also seem somewhat brain dead; some guy ran past me and hid behind a corner, went to him after which he repeated a few times and finally started shooting. It's weird, 'cause at the same time there's situations where it suddenly gets frustratingly difficult.
 
With that said, I played 8 hours without stopping. It just feels like the more linear S.T.A.L.K.E.R. I've always wanted. Too bad they didn't spend some more time polishing the combat.

hmm.. thanks for helping me decide not to touch that one.