I loved the finale.
I know someone who is trying to argue (on the basis of the wreckage during the credits, primarily) that the entire show was a dream that Jack had while dying from the original crash. It doesn't make any sense to me at all, but he didn't watch until last summer, then caught up on DVD and watched this season, and that's been his theory all along. I think he's just grasping at straws. It drives me crazy.