After too many light-hearted episodes, the writers finally get back to the apocalypse. Despite the dialogue in several episodes suggesting that progress was halted for good reasons, it was never convincing. This is what we've been waiting to see, and the writers deliver a gut punch to remind us that they still know what they're doing.
I'm very sorry to see Ellen and Jo go, especially since they were gone for so long and they were strong supporting characters. I was in the minority regarding Jo, especially when the backlash against her seemed to be based less on story and more on issues within the fandom. Ellen was sorely missed as a surrogate parental figure, though Bobby has shifted into that role more and more since the second season.
I expect that there will be some criticism for the killing of two recurring female characters, which seems to follow the pattern that minorities get the shaft on Supernatural. I even expect a few comments about sexism. I don't see it that way. While some deaths might have been questionable earlier in the series, this is the apocalypse. This is war, and these are the soldiers. The characters themselves knew the risks, and they accepted that they might have to sacrifice themselves for the sake of the world.
Jo went down saving Dean, and she made a conscious choice to make her death count in the end. In other words, she went down like a Hunter. Ellen's decision to stay with her daughter and sacrifice herself was both pragmatic and emotionally charged. In the end, if Ellen had not stayed, Jo wouldn't have held out, and the bomb wouldn't have gone off at the right time. I think it was a fitting end for two Hunters. If anything, they received the kind of heroic sacrificial moment that is typically reserved for male soldiers in war movies.
There is the small matter of the attraction between Dean and Jo. Frankly, I had no problem with this, and I really liked the fact that they had Jo deny Dean the "last night on Earth" play. While the writers never went down that road during the second season, they had clearly established the attraction, and it made sense to pay it off at the end. Had the apocalypse never come, would Dean and Jo ended up together? I seriously doubt it, but they had a history, and this was a good way to acknowledge it.
I also liked the portrayal of Meg and Lucifer in this episode. Rachel Miner is deliciously evil as Meg, and her interplay with the Brothers Winchester and Castiel was well done. I suspect that there may be a twist with Meg before all is said and done. A rather critical point was brought up by many of the characters: if Lucifer considers humanity a plague on creation, why would he keep demons around when they were just human souls twisted to become minions? If Lucifer wins, the demons are expendable. If Lucifer actually forces the final battle and then loses, the demons are finished. As Crowley says, the best option is to fight to maintain the status quo.
It doesn't surprise me that the demons collectively never thought of that. After all, the angels collectively didn't recognize that God's absence might have been part of the plan. The minions bound to service on both sides were never meant to see their true role in the endgame. Only Castiel and Lucifer seem to get it: the entire point of it all comes down to the choices of those granted free will. It's all about humanity, and in that sense, it's been about the Brothers Winchester.
This is one reason why the interplay between Castiel and Lucifer was so compelling. Neither one of them seems to understand the true nature of the situation. Lucifer chose to rebel against the will of God, and his self-justifications cannot mask the ugly truth of his intentions. Castiel, on the other hand, rebelled against his fellow angels, who themselves had turned their back on God. Castiel didn't fall; the rest of the angels did. It's just that none of them have recognized that fact yet. The difference is faith: Castiel still firmly believes that God is still there and worth searching for, while the rest of the angels have assumed that God is dead.
For this reason, it occurs to me that God may not only be waiting in the wings, but he may have prepared himself a vessel. Thinking back on the analogy from "Changing Channels", there were parallels drawn between Michael and Dean, Lucifer and Sam, and God and John Winchester. Assuming that John Winchester is not going to be brought back as some kind of avatar of God (which would be one predictable direction), who else could play that role?
The answer might lie in two unexpected but interesting possibilities. One would be the sole remaining father figure for Sam and Dean: Bobby. That might explain why he was paralyzed, and why the writers are having him struggle with finding a purpose as a Hunter and as a human being. Bobby may be on the path to be offered the chance to make a profound sacrifice on the behalf of his "sons". Given Bobby's personality and attitude, it would be an ironic choice.
But if the writers wanted to avoid the notion of having a human being act as God's vessel, they may have already constructed an alternative. Castiel was brought back from the dead for a reason, and he has always served as the heavenly support behind the Brothers Winchester. Thematically, it would make a great deal of sense: Castiel searching the world for God, only to find God within himself. As the only angel to retain his faith in God, what better way to be rewarded? I think it would be a worthy end to Castiel's character arc.
Whatever the case, this episode continued to demonstrate that Supernatural all comes down to human choices. Even during the apocalypse, it all comes down to free will. Things are getting dramatically worse, now that the Angel of Death has come on the scene, but the Brothers Winchester will keep fighting.