If you haven't seen the episode and are intending to watch it, I urge you to not read any further because I am going to be discussing what happened and I don't want to spoil it for you.
Now on to my take on what happened...I am going to go ahead and join the throng of viewers to post about it, if for no other reason than posterity.
At the beginning of this season we see Jack on the plane experiencing turbulence. It's my opinion that's when he died. Rose looked over at him and said "You can let go now." Jack is confused by what she said at first so she repeats herself. I think her comment was meant to be more profound than literal. Jack lets go of the arm of the seat but not of the life he wished had turned out differently.
At the end last night his Father tells him that some of the people died before him, which we saw throughout the show, and others long after. I am assuming the latter is a reference to the people who did get off of the island or stayed behind and went on to live the rest of their lives more or less normally. So like his Father tells him, everything they experienced on the island was real. They were not dead at the time of the crash, and they all lived through what we saw on the island.
So technically I think the flash sideways was also a little bit of a flash forward to a limbo they were in until they had all died. I am also guessing that it could happen simultaneously because time in the afterlife is no longer relative.
The part that bothered me was when Christian said that these people meant the most to you in your lives. Well what about their friends and family before they got on the plane? Sure some of these people didn't have good families and friends but many did and I felt that sent the wrong message.
What I don't understand is if you were going to create your own little niche in your limbo world while you're waiting for everyone else to show up, why would you subject yourselves to such traumas like getting shot in the case of Sun, being in jail like Sayid and Kate, or still having a drug addiction like Charlie. And why would Claire still be pregnant?
A large part of the show was watching most of these characters work through their life issues they had before getting on the plane while they were on the island. So in my opinion there was no penance required in limbo.
I did think it was very appropriate that Ben did not go into the church because he still had things to work through. It didn't bother me that Walt wasn't among the group, because he was a child when the plane crashed and I can assume he went on to lead a normal life and only gained his baggage after he grew up. I felt that Michael, Mr. Eko and a few other characters should have been in the church though. Perhaps Mr. Eko building the church on the island was symbolic of what was to come, although I am not sure that the writers had thought it all out that far yet.
Overall however I found the ending disappointing. The series was a convoluted mess with too much moving forward and backwards through time. Too many questions left unanswered about the island itself and why certain things happened. I felt too many plot lines were abandoned from one season to the next and that much of it was just for ratings and to keep us watching, despite being meaningless in the end.
Maybe the great point of the show really was that lots of things in life seem meaningless but have a hidden meaning? I have no idea. I do know that the last three seasons were tedious for me, but I kept watching for the simple fact of waiting for the finale where we get our answers...which we really didn't...and I was fairly certain we wouldn't. But I had hope I would be wrong. I was left last night feeling bereft and as if I had wasted wayyyy too much of my own life watching water spill through a sieve just to go down the drain. If these two writers come up with another show, you can count me out of the viewing audience.
Sure a lot of viewers would have been unhappy with a happy ending because it would have seemed trite, but I wouldn't have been one of them. I like happy endings. Life has enough confusing issues with it's myriad of trials and tribulations and I don't think TV viewing should be one of them.
Just my take on it!