I've downloaded a Russian version to preview it because the anticipation was killing me; I loved the original stalker and I can't wait to get Stalker: CS
FYI: I do not encourage video game piracy in any way, and I don't care if you pirate or not - and I also guarantee that in 3 days i'll be getting Stalker: CS on Steam :-o ps: any attempts to poke at me for piracy will simply be met with SS's of my Steam library or photos of my game library, lol - anyways.
My thoughts from trying this demo:
Graphics are incredible, extreme settings at 1680*1050 is at least as taxing as Crysis for my system but its quite playable.
Sound quality is excellent even with my onboard motherboard sound, its a good bump up from Stalker: SoC in that they use more audio channels by default and the SFX in general are crisper highs and deeper lows - overall nice improvement to to Stalker: SoC's sound library.
Story: No idea, its all in Russian so i'll just have to wait until the English version is released.
Stability wise, i've had no crashes yet; so i'd say it seems good to go.
Gameplay in general is great - if you liked Stalker: Oblivion Lost's general gameplay then you'll like Stalker: CS's. Where Stalker: CS and OL differ though, is that Stalker: CS uses the Stalker: SoC armor/damage model, anyone who has played Stalker: OL knows how powerful the guns are in that mod. Stalker:CS has a great new weapon mod system and includes a repair/damage system for gear.
Faction wars so far seem very well developed - npcs act on their own independantly and can even take some objectives without player assistance. Likewise, counter-attacks from friendly/opposing forces seem to be quite furious - the enemy definitely knows when you're attacking their territory, and likewise your allies will send units to the front as soon as they can. All in all, it seems quite functional; combat AI seems to have been improved decently too.
In general if you liked the original Stalker, then its pretty much guaranteed that you'll like Stalker: CS - ignore the IGN review, its terrible and not worth your time; i'll say this much though, if you DIDN'T like Stalker: Shadow of Chernobyl, then you won't like Stalker: Clear Sky - this game isn't for everyone, and the demographic they target is a lot different from the popular North American demographic for gaming.