Lost really dropped the ball in season 6. Having now seen the series through to completion, I among many was bitterly disappointed with the series finale. The current package art tagline, "all the mysteries will be revealed" does not ring true as the show's wrap up acrimoniously avoids answering the mysteries long established and left unexplained and instead cops out with an ending that fans themselves had actually bettered, in the ongoing speculation over the relevance of the "sideways" theme of the final season.
LOST is far from a perfect show. Like many, its first season is largely considered to be its strongest and from an accessibility point, this is true. Season 2 begins to wane in quality of the story with unnecessary flashbacks which reiterate the first season stories, and superfluous storylines like Sawyer and Hurley's quest for a noise-making treefrog.
Season 3 sees the show begin to rev up again, with a far more balanced year of revelation vs filler and finally, a packed season finale with genuine "WTF!" moments...
Season 4 and 5 I consider to be the best of the show. Season 4 establishes flashing forward rather than back to characters' lives, and the introduction of compelling new characters on the island including Faraday, Charlotte and Miles. Season 5 continues the brilliance of 4 but ups the ante now crossing time and space itself, with the ensemble cast divided in completely separate positions. This year features the show's 100th episode, and the remaining episodes rev up to the last annoyingly brilliant cliffhanger.
So we come to season 6. The heights of the last 2 years and elaboration of the mythology, coupled with regularly returning plot holes like Walt and DHARMA led me to have huge expectations. Yet sadly, LOST season 6 suffers from what you might call "trilogy-itus" so common in film series' as the last part cannot match the brilliance of what came before. Conclusions, when offered, are more logical and predictable than outstanding and the series mostly suffers from three different groups of people sitting around while not actually doing anything significant.
The ending encourages you to accept their denial of answering questions, of it being irrelevant in the grand scheme of things. But it doesn't sell after 6 years of waiting for the mysteries to make sense. Up to a point, Lost is an incredibly intelligent show, that for a time demanded complete concentration and recollection on behalf of its captive audience.
But 'The End' doesn't deliver, and fans are left emotionally rewarded with cheap reunions, but intellectually disappointed. The real hook of the show is itself 'lost' along the way.