How do you tell a science fiction story when you don't explain the rules? How do you have characters when you don't provide them with motivation or purpose? Where's the story if there are no stakes, just a lot of things happening at once? How do we react to death and life-and-death decisions when there are no consequences, just alternate realities?
These are the problem that the Lost audience has tried to deal with in Season 6. At this stage, the show is either dazzlingly groundbreaking or another Galactica-sized cluster-fail. The only question I have left is: do the personal struggles of the characters serve the Island (the tiresome Jacob v. MIB conflict), or has the Island acted as a catalyst to help the characters resolve their personal issues in the alt-universe? In other words, why have we followed these characters over the course of 6 seasons? What has been the point? Does the show actually have anything to say?
I'm rooting for the alt-universe because the Island has never been anything but trouble. Magic, smoke monsters, Others: escapist nonsense and false hopes. What really matters is the world and how you live in it, not a lot of crazy mysteries. Where did the Polar bears come from? What do the numbers mean? Who is Jacob? Ultimately, answers to questions lead to more questions, as Mother said, and one MacGuffin unfolds to reveal the next MacGuffin. But how does our desire to create meaning out of noise provide us with any real understanding?
My guess is that it can't, or won't. What Lost needs is a human sized ending that allows Jack, Kate, Sawyer, Hurley and the rest to find their human sized destinies. Not a lot of smoke and mirrors.