I've played all three Stalker games with their respective Complete mods, and they are truly amazing. Artistpavel did an excellent job on them all, even Clear Sky. I wouldn't even consider playing vanilla without the Complete mods installed.
His site, with the promotional trailers etc. as well:
http://artistpavel.blogspot.com/Anyway, very happy to see that development is continuing. Similar to what the previous comments said, these games are among the best I've played in the last decade.
This comment was edited on Jan 12, 2012, 01:50.