I hated the ending. In fact, I believe it was the worst ending ever for an RPG I've played (granted, I haven't played that many).
Last night, I finished STALKER: Clear Sky. Was pissed at that ending too. Though not because of the poor story (I wasn't paying attention in the first place, unlike Fallout 3 where I actually read/listened to everything the characters said). Just because they put the point of no return really early in Clear Sky. I had a bunch of stuff I was going to sell for money but there wasn't a trader nearby so I planned on doing it later. I unknowingly crossed the point and I wasn't really prepared. I hadn't upgraded my armor yet and I didn't have enough cash to repair the armor when I got the chance halfway through the ending portion. So I had to do the last battle with crappy, un-upgraded, broken armor. I died so many times (thanks to my lack of armor) that I got frustrated and installed a "God Mode" mod in order to finish it. And after that I couldn't do anything. No going back and selling my gear to upgrade and repair my armor. No trying my new FN F2000 rifle on groups of bandits. Just the chance to revert back to the beginning of the last area again.
I am planning on playing it again but cheating (I know, I know, please don't hate) so I can get all my gear back from the beginning. Now that I have a better idea of what to do I should be able to do better at certain things I screwed up the first time (for instance, the Stalkers took the depot from the bandits without my assistance the first time but it resulted in there being only four of them at the base after it was captured, rather than what should have been a much larger force).