

I think in hindsight, the ending is not that bad. Especially when you compare it to disasters like Game of Thrones and Pretty Little Liars. I haven’t seen the series in a few years, but I think watching it now on streaming is a completely different experience than tuning in every week.
I found it hard to follow the mysteries and plot week to week. To be fair, I was young, my attention span was short, and I didn’t participate in any discussions or forums which would have been helpful for understanding.
A lot of people didn’t understand the plot in the church was a sort of alternate reality where people were reunited in the afterlife. So people were upset that they were dead the whole time and that was too obvious. But that is not the plot, it’s just how people misremember it.
Love it or hate it, I think the ending wrapped up enough of the plot to be respectful to the audience that fell in love and watched all those seasons. I personally kind of appreciate that some things felt unanswered. It made the whole tv show seem more mystical without being tied up in a perfect bow. But I am not prone to poking too many holes in the fiction I consume. I find it relaxing to just suspend my disbelief and enjoy.
It has been several years since I watched the series, so I forget some of the ‘lore’. But as I remember the finale, there are 2 timelines or realities going on. The island good vs evil and the church reunions.
The church is a reunion of people who have lived and died on the island. The plane crash still happened, the events on the island still happened, it wasn’t some collective fever dream or purgatory that the passengers were living. The church just shows the characters after they died, but they are reunited with people they bonded with on the island. For example, Charlie is reunited with Claire. Those two people wouldn’t know one another if they did not survive the plane crash.
If someone has seen it more recently, maybe they could provide a better example? That’s the best I can describe it.