S.T.A.L.K.E.R.: Clear Sky - Review @ CrispyGamer

Another middling result for STALKER: Clear Sky with CrispyGamer's review recommending "Try" rather than "Buy".  Technical issues are the main culprit:

While the improved AI adds to the game's believability, it's also plagued with technical bugs that take away from it. Clipping and collision detection problems mean that a character might walk through another or through a wall, or slowly push another character across the ground as he walks into him. Characters will walk in thin air, about a half-foot above the stairs they're supposed to walk on. You can get stuck in odd crevices with no way to get loose.

But before you download the 56 MB patch to repair some of these graphic glitches, be forewarned: Installing this sucker will delete your saved games (I found out the hard way). This is too bad, because the game's DirectX 10-supported graphics are one of its strongest merits until you see someone with half a leg stuck in a rock or doorway. Therefore, take heed and install the patch before you begin to play the game.