As for Lost, my brief, meta-ish thoughts with vague spoilers:
On the whole, I liked how they ended. I'm glad they didn't try answering every last thing, nor even some of the biggest questions of the show itself. I'm glad that they didn't even try to explain just what the Island is, the light at the heart of the island, or who originated there before Jacob et al. because mystery is a good thing in a story, even a story that's ended. We might crave the answers, but they're rarely satisfying. The alternative to question marks is midichlorians, and I like my Force with question marks, thankyouverymuch.
I'm also pretty much on board with cleolinda's argument that:
Because Lost put it all out there, and you may think it succeeded or you may think it failed, but even if it failed, it had a damn good time doing it, and I had a damn good time watching it, and even at its most frustrating, people loved it and were engaged by it."
Even if you think the show failed -- I don't, but anyway -- it had the guts to even attempt to blow our minds, to turn it all to eleven and dazzle the shit out of its audience. Lost tried to do something different and daring and crazy and challenging and ambitious, to not be yet another cop show, or hospital drama, or mindless sitcom. Those stories have their place, too, and I don't begrudge people for loving them. But it's the stories told on the edges, the shows that gamble big with plane crashes and polar bears and crazy-ass disappearing islands that push the boundaries of TV and storytelling, it's those stories and shows that people remember and talk about years later, and it's those stories and shows that open more doors of possibility. As cleolinda puts it, Lost swung for the fences, and I for one sure as hell enjoyed watching them do it.