LOST was the story written by its producers to be what they wanted to it to be. There is nothing any viewer or fan can do to change the story that was shown to us because it was not our story but the writers vision. It is like reading a book. At the end, every person has an opinion on whether the writer accomplished his/her goals.
Did TPTB accomplish their goals? Probably.
Did TPTB deliver a totally satisfying ending? Probably not.
A list of growing disappointments is a factor of the new, unanswered questions posed by the finale:
1. A vague explanation of the sideways world (as a construction by Jack's friends waiting for him to arrive so they can all move on; some sort of partitioned waiting room in heaven) was fine, but the ending did not clearly tie together the pre-island, island and post-island events. Were those events "real," partially real, or another "construction" by Jack's family or friends? What was real and what was imagined and what was mixed surreality? The current debates on whether the main characters died before, during or after the crash of 815 should have been settled by the writers in the last episode. It has been a focal issue from the first episode: did they survive the crash? It should have been clearly answered. Many point to Christian's comments in the sideways world that Jack's life was "real,: but he said the sideways world was also real.
2. There was no concept of "time." In the sideways world, Christian said there was no past, present or future, just "now." Except, throughout the season we saw a linear progression of days or weeks in a realistic world of Desmond running around trying to "awaken" people's minds so they could gather and leave together. If there is no concept of time, how can anyone be sure that the island events happened before the sideways world?
3. There was no explanation of why people needed to be "awakened" in the sideways world. They were all dead. Supposedly dead at different times, some before and some after Jack's demise. Was this just Jack's vision of purgatory? If so, can the characters cross over multiple times with different groups?
4. If the island was the most important bonds the 20 characters had during their real lifetimes, and that is the sole reason why their souls congregated for the journey to the after life, then our characters who left the island must have had no significant life experiences until their alleged natural deaths. Example, Aaron had no deep bonds with anybody so he was "re-born" as a baby in death? That seems profoundly unfair and sad. If people survived the island to lead real lives, their families, their children would have been greater bonds than the islanders. (Once combat soldiers who lived through hellish conditions go home, I don't see the overwhelming need to re-connect with their squads especially if they are dispersed over different places).
5. Why did Hurley, as the island protector, thank Ben for being a good "Number Two," when there was nothing shown. People have speculated that Jack died in the finale, but his soul was in limbo was decades to centuries. It is also speculated that the sideways world was Hurley and Ben's creation to hold their island friends spirits together until they "arrived" for their next journey. But that theory does not explain why Hurley and Ben themselves had to be "awakened" in the sideways world.
6. Many people were really disappointed to find Sayid's soul mate to be Shannon and not Nadia. People also observed that in the final gathering, Boone and Locke had no companions for the next journey. So there was no clarity on what it took to be "ready" to move on. It is interesting to note that the symbolic seating arrangement in the church mimicked the seating on Flight 815. That leads some to speculate that 815 was purgatory number one; sideways world purgatory number two; and the church scene the lift-off of eternal life.
7. One of the major criticisms of the story telling is that the ending left many, many questions with the answer "it did not matter." It is almost shocking that for the amount of time, energy, research and effort in making the Dharma stations, the temples, the hieroglyphs, the Blast Door map, the science fiction elements of time travel or moving a physical island were all immaterial or irrelevant as foundational facts for the story's resolution and explanation of character enlightenment. Those mysterious island elements were mere props or red herrings? The final explanation was that LOST was always about "character development." But that was only half of the overall story.
8. Another lip biting irritation was that the writers failed to explain "any of the rules." Jacob and MIB had unspoken rules which may or may not have been broken throughout the show. It seems that the island guardian can make up the rules. How is that possible if the island is a real physical place with natural and supernatural forces? "There are no rules" explanation for the island context is a weak way of not trying to explain all the contrary elements and actions the viewers saw for six season. Some could call it an intellectual cop-out.
9. In the same vein, what really was the smoke monster? Did it exist before MIB's body was tossed into the cave? What was it made of? Who were the skeletons in the life force cave? Who were the other children running around taunting Flocke? What was the island? Why did it need to be protected? Why were some characters deemed "special?" Why did Desmond's fail safe body fail when Jack's plugging the opening worked? Why did the cork need to be in place? What were the dynamics of the earthquake lava in the cave vs. the green light that reappeared once the hole was capped? And why didn't Jack turn into a smoke monster? Is Michael still a trapped soul (a whisper) on the island? What were the writers true visions of humanity: are we reincarnated? do we have only one soul? is there a heaven? is there a hell? what is the key to a person obtaining eternal happiness? TPTB did not have lecture us on theology to give us some explanation of why these characters found their way to that place. The ending was more a secular humanism vibe than any one religious context.
LOST was a roller coaster for fans to watch, debate, interact, speculate, and predict. From a television standpoint, it was a good show, highly entertaining. Many people found the end gathering emotional, touching . . . some compared it to a real funeral. For the amount of time invested with the characters, combined with the angst of the show concluding forever, there would be some emotional release. But for some, the ending was anti-climatic. The alleged "war" over the island turned into a mere duel. The the vast amount of unanswered questions muted the significance of the ending. There is plenty of room for a valid criticism that the show could have tied up more loose ends in a coherent way. But, if the writers had painted themselves into a corner by throwing so many conflicting elements at us as filler, then their decision of moving off quietly into the light was their best means of ending the story.
In summary, I felt underwhelmed by the ending. In my mind it could have a more dramatic and better ending. I am glad it resolved a major piece of the Big Premise. The fuzzy good feeling for the characters at the end was okay. Early in the episode I thought TPTB would not be able to pull off any good ending. I thought to myself they should have ended the series with the last episode of Season 5. (Now that would have kept the debates alive for a long time). But when sideways Jack pulled the x-ray over his face, I knew immediately that this was a symbol of his own death mask; that the show really was about death and the after life. So I let go and let the writers conclude their tale in their own way.
LOST was one of those shows that made you think outside the TV box. The on-line communities of commentators, bloggers and fans helped bridge the gap between episodes with their thoughts and theories which greatly added to the overall LOST experience.