Stalker is a fantastic franchise, and this game is the perfect closing for the depressive story. *nano-spoiler* Strelok, the ♥♥♥-kicker and protagonist of the first game and the most important character of the series dind't get a very good ending in my playthough... but that's the beaulty of this game. *end of nano-spoiler* What you do and what you didn't do is important in the end. This is the best of all three games technically, but it's not better than the first in terms of mood. Maybe that's just because Shadow of Shernobyl was the first one I played, I don't know. If you like FPS and RPGs, and think that the odd relationship between Call of Duty, Fallout and Penumbra should result in a cool ♥♥♥♥♥♥♥, genetically threesomely impossible, ucranian child, you will fall in love with this gem of a series. They are cheap even in full price, I asure you.
And one more thing: I am a HUGE fan of Fallout series (but yeah I prefer the original. More Mad Max and less America ♥♥♥♥ Yeah than the PFS ones, but still) but S.T.A.L.K.E.R is better. You shoot, your bullet has a parabolic trajectory, it hits the head, the enemy dies. No "5 hits in the head because ♥♥♥♥ realism and fun, ATRIBUTES AND MATH!!!" If there is an enemy around, you see it. No "I can't see because of a calculation between atributes and random enconter generator" or anything. Of course, this is a matter of taste.
Also, this game is almost bug free (it was 100% vanilla bug free in my playthough, at least). Perfect.