Sometimes the desire to repair a less than ideal situation can lead to unexpectedly unfortunate results. Giving Clark and Lana better closure than the strike-induced video departure at the end of the seventh season was a good idea. Setting up a good explanation for Lex's extended absence due to Michael Rosenbaum's departure was another good idea. Twisting an already great eighth season arc completely out of proportion? Not so much.
Fans of the Clark/Lana relationship will no doubt love this episode. Instead of the nuanced conversation that marked their reunion in "Bride", Clark and Lana revert to the super-emo "my entire world is you" mentality that was played out seasons ago. All of Clark's personal growth is erased, and not one other character seems to notice.
And that's the problem: there is no acknowledgment of context. This story seems to take place in a vacuum, where only elements from previous episodes that tie into the needs of this story are mentioned. Whatever happened to the threat of Doomsday? There was some good progression of the Oliver/Mercy plot thread, but it was still shoved too far into the background.
Most importantly, what about the growing attraction between Clark and Lois? As it was handled, Clark was choosing to move on from Lana to Lois, as people always must do in their lives. It's great that Lana chose to take control of her life and find her own power, but why did that force Clark to drop everything, as if the rest of his new life and Lois were a collective second prize?
This is all the result of how the story was handled. It could have easily been reframed to give Clark and Lana the chance to recognize that they were no longer right for each other. Imagine if Clark and Lana, after working together, came to the realization that they were no longer quite so compatible. Not only would it have been in keeping with "Bride", but it would have given both characters considerable growth and maturity.
Instead, the two are forced apart. Leaving aside the rather ridiculous idea that Lana wouldn't know that Prometheus was designed to absorb the properties of kryptonite as a weapon against Clark, given her supposed research into the project, the entire situation is contrived to force Clark and Lana apart against their will. Which means both of them have their lives and choices made for them.
At once, the entire point of giving Lana a true sendoff is rendered moot. Lana doesn't pay some personal price for her decision to grab artificial power rather than develop it on her own through training and hard work. She's forced to be apart from Clark. She completely loses agency of the choice to stay or go.
This is not confined to Lana, of course; Clark is forced to accept that he cannot overcome this situation through force of will. That particular moment is relatively effective, and had Lana left Clark broken on the floor, it might have been even better. But the point is that Clark is being forced to abandon what he really wants, thus implying that whatever comes next is merely a concession to a no-win situation.
This also brings no resolution to the fact that Lex knows everything about Clark, and is now truly presumed dead. Since Lex isn't supposed to know everything about Clark in the future, how does that work? The only possible way to solve this problem is to take the series far enough down the road to demonstrate just how different this version of Superman's formative years will be. (Which is not necessarily a problem, considering how "Smallville" has always been in a world of its own.)
Ultimately, this episode confirmed all the fears of the fans who hated the previous episode, let down the fans who were willing to give this twist a chance, and threw a surprisingly strong season into total disarray. The writers are going to have to work overtime to work their way out of this hole.