Pretty much. (Although per Black Knight below it didn’t actually say “COEXIST”. I’d have bet it did)
Here’s a “I didn’t enjoy the ending, but I’m still trying to be fair” synopsis.
[spoiler]
The second-to-last season ended with a nuke going off in the past and (as far as we knew at the time) creating a second parallel time line. There was all sorts of cool drama in the last season* as it looked like the parallel time line was “What would have happened if the plane crash in S1 hadn’t happened?”
As time went by, we figure out that that the parallel timeline had diverged much earlier and the characters who were affected by the magic immortal guy had apparently not been affected by him in this timeline. So the con-man had become a cop, etc. One after another, the characters remember the main timeline.
Eventually it turns out that the parallel timeline isn’t a parallel timeline at all and..um..it’s like a waiting-room for heaven. All the characters died at one point or another in their post-show lives and nothing they did in their lives made any difference after about season 5 because they all had to get back together–no friends, no family, no loved ones that weren’t in the first 5 seasons and they all had to remember before they could all move forward. They didn’t just die all at once, they went on and lived long (or not) lives, but when they died, they all ended up in heaven’s waiting room and hung out there, amnesiac, until all the people on the plane crash showed up.
Finally, the last episode has everyone racing towards a church. Almost everyone in the parallel timeline has remembered, but Jack (the doctor/main character) doesn’t. Finally they get into the church, and everyone is paired up with their TROO LUV (except one guy, who’s NOT with his TROO LUV, he’s with some irritating crazy, whiny bimbo he went on one or two dates with and boinked once–which, I think both the pro-ending and the con-ending agree was totally stupid–why wasn’t Sayid with whatshername who he spent most of his life loving and sacrificing for rather than the incest-bimbo?) and when Jack joins them (from a door behind the pulpit) they all walk through the big glowy front door into 100 watt/dry ice smoke heaven. [/spoiler]
The problem is that while (weenie-ending or great-ending debate aside) it ends a lot of the character arcs, it resolved absolutely none of the mysteries from the previous 5 seasons. And honestly? For me, the character drama were the least interesting parts of the show for me–it was the mysteries that I loved (the stuff with The Numbers, the Hatch, etc) were the parts I loved the best. The endless Jack loves Kate who has the hots for Sawyer who loves Juliet…but can be lured away by Kate (who sucks and ruins everything) drama was stuff I suffered through to see more of the mysteries.
*None of which had anything to do with the drama from the previous what…six? seasons, but still…interesting