ok ok wtf you are making me not want to buy it. Clear Sky was, if i recall correctly, the last physical copy i have ever bought, and what really pissed me off was that GSC/DeepSilver released patch after patch after patch in the early days, and every patch broke the saves, and every patch broke the game in different ways. The game was eventually playable and i completed it, WAY before the community patches, and all that "Complete Edition" stuff. I was quite angry at the time, but i realise that anyone who got the game 3-4 months after launch will have probably enjoyed a relatively stress-free experience.
Also, at the time, i could only compare Stalker to Oblivion for how gorgeous the game looked; on top of that, while oblivion is just a pretty face, Stalker has a "interactive" environment, which is the anomalies. Never mind the day/night cycle, that looks pretty but it's a gimmick. Dodging semi-invisible traps while relying on a crappy detector to find artifacts is a great minigame of its own.
The one critique i can easily raise to the Stalker series (aside from the idiotic punctuation of S.T.A.L.K.E.R.) is that the 3 games are too similar to each other, with whole maps lifted off previous games. But it's by far one of the best single-player games i have ever player, really up there with FEAR. The guns are great, the monsters are great, i love the anomalies, the eruptions, the art style (but NOT the music), the environments look gorgeous.
Sure the missions were bugged, because they were heavy on the scripting - it's not just a mob spawn trigger. And while i hated it at the time, i love that the devs put in Clear Sky a section where you are quickly shown that you can go that way, but you CAN'T go that way (the machinegun nest at the entrance of cordon). Stalker will kill you without a second thought. Some of the guns were unbalanced yes, early gunplay was bad, but that's half an hour out of 20+ hours of game.
.. also it's a game that loses a lot once you know what you need to do. I played it again some time back and i just rushed the first 2 maps, found the first moron with an AK, put the shotgun to his face and took his AK, then rushed 2 more maps, found the first idiot with a M16 and dumped the AK in his face, then used that M16 to snipe some Monolith and grab a G3 and BAM!, endgame weapon.
It's a lot more fun on your first playthrough, when you first discover new weapons, meet new mobs, see new maps, and i hope, really really hope, that they have NOT YET AGAIN reused the same maps. Obviously i expect that there's gonna be bloodsuckers and AKs but i hope that they bring more than just a new coat of paint.