(Ed. Note: I am currently writing up this review while recovering from having my gallbladder removed on Wednesday, 19 May. So if it seems like it's not as coherent as usual, blame it on pain medication and my need to take frequent breaks as I write! Thankfully, I should be back to relative normalcy in time for the finale!)
With this penultimate episode, there is little need for new mysteries to solve. Instead, it's all about resolving long-standing plot elements. In typical "Lost" fashion, it's not always obvious that a plot has resolved or even how! But the answers are there, and many of them confirm or support the speculation in the review for "Across the Sea".
It's always important to remember that even though the mythology depends on the conflict between Jacob and Adam (the smoke monster), this is only meaningful in terms of what the main characters have been dealing with since the crash of Oceanic 815. This is readily apparent in this episode. Jacob's actions in "Across the Sea" may have started the story, but it's always been about the journey taken by the survivors.
Jacob's decision to finally explain why he orchestrated the crash of Oceanic 815 helps to bring the series full circle. Many fans had already caught on to the double meaning of the series' title, and as it turns out, that's precisely the quality that Jacob was looking for in his Candidates: people who felt alone, lost in the world, unable to break out of their negative patterns. In short, someone exactly like Jacob, as he admits himself.
It explains why Kate was supposedly eliminated as a Candidate, though it's rather annoying to think that Kate doesn't have a higher purpose in the story, to explain her prominence from the very beginning. And it definitely makes it clear that Jack was always going to be the one to take Jacob's place. Jack has always been searching for his place in the world, as exhibited by his never-ending control issues. Now, the man who always wanted to fix things has the opportunity to do just that.
It's good to finally see Richard, Ben, and Miles coming back into the story. It's a little annoying to see Richard taken down so easily, but it does underscore how Richard has been operating under his own illusions based on partial information. It wouldn't be shocking to see Richard again, but considering how many supporting characters have been killed off, his apparent death could be permanent.
Widmore survived just long enough to explain his actions over the course of the series, if in a rather abbreviated manner. Widmore's desire to kill off everyone on the island aligns well enough with Adam's ultimate designs. Widmore's assertion that Jacob came to him and explained the error of his ways suggests that he had been fooled into fighting on the wrong side. Certainly Widmore's comments to Locke in "The Life and Death of Jeremy Bentham" suggests that Widmore knew a war was coming and that he had been convinced that wiping out everyone on the island was the right move. Those actions led directly to Adam's ability to use his "loophole". So in general terms, it all fits together. (Although it was disappointing to learn that Widmore had not been in contact with Jacob all along.)
As always, Ben's motivations are questionable. Sending Miles away with a walkie-talkie to wait for orders was definitely a clue to his intentions. Selling out Widmore was a means to an end on two levels. First, it gave Ben the opportunity for his promised revenge on Widmore, once it was clear that the "rules" no longer applied.
Incidentally, what "Across the Sea" and this episode firmly established is that the "rules" have never been fully explained because they were, in effect, arbitrary. Originally, Eve set the rules, and Jacob and Adam simply assumed them to apply. Then Jacob took control, and established his own set of rules. It's easy enough to assume that Ben and Widmore either followed their own rules, or assumed that the rules between Jacob and Adam (perhaps passed to them from Richard) applied to them as well. In either case, as in the real world, the "rules" only apply so long as those bound to them agree they apply.
Second, Ben killed Widmore as a deliberate way to gain Adam's trust. In order for the events of "Dr. Linus" to have any meaning, Ben cannot be giving in to corruption for the purpose of survival. Instead, looking back on it, Ben was doing everything possible to derail Adam's plans. He shot Widmore once he knew enough to take action and, presumably, to try to stop him from telling Adam what Desmond was supposed to do. And Ben was ready to kill Desmond if it meant derailing Adam's plans, if his expression at the end of the episode was any indication.
Ben has seemed ready for a redemptive act for a while, but would any such action ever be truly acceptable, given the characters' innate shades of grey? Ben was always insistent that the ends justified the means, and that he was really the good guy. Now that he knows he was manipulated himself by Adam for decades, he seeks to have one moment where he fools Adam and saves the day.
But it's equally clear that Jack is going to need Desmond as well. Desmond appears to be the one person who can survive the Source without being transformed; that would appear to be why Jacob had asked Widmore to bring him to the island. So if Ben tries to derail Adam's plan to destroy the island (thus presumably unleashing hell by destroying the Source, metaphorically or otherwise), Jack and his allies would logically try to stop him. How ironic would it be for Ben to die, assumed to be a villain, while committing what would truthfully be a selfless act to save the world?
Ben's story in "Lost X" was remarkably touching in counterpoint. It would be wonderful to see Ben and Danielle together, raising Alex. It was great to see Mira Furlan again, presumably for this one last time, and it definitely served the purpose of showing how all these individuals are coming together in surprising ways.
It still all comes down to what the writers do with "Lost X". Desmond continues to bring together the passengers of Oceanic 815 (and now, even those who weren't on the flight, but are related to "Lost Prime", like Ben) for a single purpose, and it seems like it's more than simply getting them to experience memories from another life. One can only assume that this factors into whatever Desmond is supposed to do within the Source.
Back in the review for "LA X", it was speculated that it would come down to someone choosing either reality ("Lost Prime" or "Lost X"). Either Jack or Desmond seemed like the logical "candidate" to make that choice. With Jack taking Jacob's place to see this final confrontation with Adam through to the end, Desmond' nature makes him the perfect choice to make the call.
This would align well with Desmond's actions in "Lost X". Without knowing it, Widmore could have given Desmond all the information he needed to become this perfect "failsafe". It's clear that Desmond in "Lost X" is acting with purpose, bringing everyone together, and timing appears to be vital. This implies that the connection between the two Desmonds continues to exist on some level.
Perhaps Jack, in combination with Desmond, will come to the realization that "Lost X" represents not only a timeline where Jacob never forced them to come to the island, but also a reality in which none of the survivors of Oceanic 815 were ever truly alone. Plus, safely underwater, the Source would remain inherently protected, since it appears that the Incident caused the island to sink.
Whatever the case, the writers will have to reveal the nature of "Lost X", and more important the nature of the island in that timeline, in the finale. A solid case has to be made for how defeating Adam ties into the existence of "Lost X", and what the implications are of the choice, if there is one. Because while delivering everyone into a reality where everyone is still alive and complete in some fashion sounds great, the implication for "Lost Prime" cannot be ignored.
Overall, this was about as solid a penultimate episode as anyone could have expected. A number of important matters came to light, a Candidate was chosen, and the stage is fully set for the endgame. There are still a few key plot elements to resolve, but with the finale running two and a half hours, there's plenty of time to do it right.