The thing that I got out of it was why they were brought to the island.
While I forget the exact quote, Jacob said that he picked each candidate because they had nothing to live for off the island. So while it was all a bunch of strategy and manipulation for Jacob, in the end each member made a deep connection and found a purpose on the island.
While I knew they couldn't answer everything, it bugged me that the Dharma iniative that played a huge role in the first 5 seasons was completely ignored and written out of the show at the end.
In all, I think the last season really highlighted how chaotic the writing had become over the years. The ending annoyed me because it required you to forget most of what you had already watched and presented new interpretations of the facts.
It wasn't a bad ending. For me, it was just unsatisfying.