Well, it's hard to judge it. Quite buggy w/o patches (possibly even more than SoC). Once patched it's all the old "good" STALKER - superman opponents (now throwing granades at you, or rather always on top of your head), immersive but somehow pointless.
Some changes are welcome addition (imo) - like much harder artifact hunting, repairing/upgrading, or faction wars (even if there's very little point to them). But all the faults from the first game are here again (and few new ones - like mentioned grenade implementation).
All in all, if you liked SoC - you will probably like CS (just don't expect SoC done right), if you didn't - avoid.