I bought S.T.A.L.K.E.R (feck it, I can't be arsed with the Dots anymore) about a year ago on one of those two for one deals at Game and for some reason never bothered to play it. I go with the whole "My PC couldn't run it" but it could, just not on full graphics.
Anyway, today I decided to install it and play it. First opinion? It's good! Atmosphere's incredible, weapons are all nice and realistic... kind of. The story seems to be the usual sort of, rugged manly affair and the characters are all lovely and Russian.
So far, so Fallout (well... with more Russians) especially as though everythings all irradiated and mutant... ey. Not that that's necessarily a bad thing of course, because it's a formula that's been proven to work extremely well. Shove it into a different, more realistic scenario and you have what could be effectively a very worthy contender for the throne of post apocalyptic role playing games. Ok, so Stalker isn't an RPG but you get the point.
More info as I play through it!