I thought the Lost ending was ok, like a C. People over-hate it because they wanted somebody to step aside and expound on exactly what the island was and answer every single question the series ever had explicitly instead of answering it through implication and metaphor like they did. I liked the ending on the island, I just hated the resolution to the flash-sideways. It was by no means a bad ending, just...not entirely satisfying.
One thing that's interesting about the ending is that Walt got to protect the legend of Heisenberg. Heisenberg went out in a blaze of glory, and now he's a criminal legend. In the BB universe, movies will be made about Heisenberg for decades that win Oscars.