The first game was in my opinion the best PS3 exclusive game so far (with honorable mention to all the fun I've had with LittleBigPlanet). I'm really hoping this one is at least as good. (so far the reviewers appear to think so).
Earlier in the year, I figured it would easily be my favorite PS3 title of the year, but then I really enjoyed Infamous, and the more I see about Demon's Soul the more I want to play it. So now Uncharted 2 has some competition. Either way, I can't wait for my Amazon copy to arrive.
EDIT: Xeph820- I don't think playing the second game first would hurt much. The setting/story of the second looks pretty unrelated so I doubt it has many spoilers about the first. However,while the story in the first game was interesting, the first game is good enough that even if someone spoiled the complete story for you it would still be worth playing,