spoilers for L O S T
The idea that those guys were all lured to the island, and the island is a "cork"... pretty neat. They just spent way too f'ing long establishing that stuff.
The flash sideways also needed to be in jeopardy due to the island activities. As it stood, there wasn't much to worry about on the island, mysteries weren't handled well, and sending everyone to Heaven felt a bit cheap. Touching, but cheap. The final season should have quickly put things in order and then created conflict, instead of trying to stay mysterious and then slop on a little conflict at the end.
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Donny: Are they gonna hurt us, Walter?
Walter: No, Donny. These men are cowards.