Let's make no mistake; Clear Sky is a harsh mistress. You will need to mod the game in order to get rid of your personal worst frustrations. The game is punishingly difficult, has slightly broken systems but is still some how utterly brilliant once you reach the mid-late game. The story of Clear Sky is probably the best realized of the series, giving us a satisfying lead up to the events of Shadow of Chernobyl and shedding more light on the lore of the zone. If you can get past it's many many flaws then Clear Sky is a game you will love. Just don't be surprised when it's tough love.
Nothing feels quite like STALKER, but it can be an acquired taste. Call of Pripyat does away with many of the frustrations of the previous games and just functions as an excellent and unique shooter. The game is much more open, has a fully working and balanced economy, a fast travel system, a great repair and upgrade system but still retains the atmosphere and tone that made "Shadow of Chernobyl" such an alternative classic. A few notes of mods; the one modification i would recommend out of the box is the "Visible range mod" as it vastly improves the dismal draw distance and look of the game with minimal impact of frame rates.
