Wow! Lots of things I didn't expect to happen. Most everyone seems to have turned on Ben. Charlie dead. The Others get blown away at the beach. Jack & Kate in the future. Danielle and Alex reunite. Ben gets the piss beat out of him. Very cool ending.
Charlie's death was sad, but I just kept wondering why he didn't try climbing out the broken window hole and swimming to the surface. I thought about who might be in the coffin. It'd have to be someone without a lot of family/friends aside from the rest of the island crew. Maybe Locke or Sawyer, or maybe one of the Others like Ben or Richard.
The flash-forwards are going to be cool if they continue in the next season. I was wondering when they were going to run out of backstory to tell about the main characters. Now trying to figure out what they mean and if it has anything to do with Desmond's ability will be fun to watch unfold.
Seeing Walt again was kind of cool, and I expected something like that was going to happen to Locke. I imagined either Jacob himself coming to help him, or perhaps the monster, or some other vision of another person like Boone or Walt. I hope they get back to what happened with Walt and Michael soon too.