Remember J.J. Abrams's unbelievably (and characteristically) pretentious 'mystery box' talk from a few years ago? Sure you do: the one where he talked about how the most interesting thing about his precious mystery box wasn't what was in it, but the very act of wondering what was in it.
Lost is, and has always been, the box (plus a healthy dollop of Lindelof/Cuse's cheerily fallible sentimentality). That was fine in Season One; a year of open-ended questions was appropriate, even if the show's staunch refusal to deal with the actual logistics of island life was an embarrassing cop-out. But the show's disinterest in anything other than the act of watching Lost isn't a cop-out...it's contempt. Critics insisted on its allegorical value, but the show was content to allegorize itself, over and over and over, culminating in Christian's arrogant and myopic declaration in the finale ('The time you spent with these people was the most important time of your life' or something to that effect). The line is neither correct in the storyworld (Sayid goes to heaven to be happy forever with...Shannon? Seriously?!) nor true for the viewer, though I imagine it's true for Damon Lindelof and Carlton Cuse, who just won the middlebrow writing sweepstakes of all time.
Otherwise sensible people are falling over themselves to praise the overwrought finale, but let's be honest: the best episode of Lost has less to say about the lives of actual human beings than the worst episode of Deadwood.
(The best episode of Lost, if you didn't know, was 'The Constant,' a grand love story that (let's be frank) was less about lovers than about the familiar tropes of cinematic love stories, with a bit of sci-fi syrup spread across the top.)