Wow @ the graphics. Just wow. They're very good on Full Dynamic Graphic Mode. Even more gorgeous, if you turn on Enhanced Full Dynamic Graphics mode -- which is what I have it on. I have most of the stuff on High (details, objects, etc etc). Draw distance is in the middle. Namely, I got AA and AF off. Running in 1024x768, always above 30 frames per sec (according to FRAPS) -- as long as Field of View is off. (Field of View on can be anywhere from 18 frames or above, is what I've experienced).
Crashes; had it crash twice. And that was with FRAPS running. Without running FRAPS, it ain't crashed on me yet.
So, here's my take -- you liked STALKER: Shadow, you'll probably like this. Unlike Shadow, which thrusts you into the action off the bat, Clear Sky takes a little bit of time to hold your hand and give you a short tutorial. Oh, then it thrusts you into the action -- and lots of it.
The action and bigger shootouts rock here. The Swamp was cool -- basically, two factions waging war here; from what I've seen, I think this is how most maps are set-up, with at least two factions fighting over turf all over the map. and you can help either. And, the AI, on their own, just goes to war with each other. So, often, they'll be shootouts and missions just popping up from out of nowhere -- even more so than the Shadow. They're often very big shootouts, too. So, you definitely want to loot bodies for equipment from the dead, since you're definitely going to need it -- especially health kits and even more so the bandages (b/c you'll need a few to stop bleeding).
You thought Shadow was tough? Ha! Clear Sky's AI's much rougher and tougher; it doesn't miss very much. And this is on STALKER difficulty (next to lowest). Shadow's STALKER difficulty was easier than this. Expect to die. A lot. Saving and quicksaving a lot is a must here.
Will give this more time and whatnot. Now, if I can through this area in Cordon where I keep getting sniped, I'll be alright...