First and foremost, I must give the producers and writers credit for choosing one of the most unusual titles in recent memory. I'm sure this one raised a few eyebrows. Maybe it's just how I was brought up, but that was always considered a relatively vile thing to say in public. Times change, however, and I suppose this is just another example of how much they change. Besides, it's not like they're particularly wrong.
Much like the previous episode, this is a stand-alone affair with plenty of connections to the overall arc. And, as usual, the strength of the episode is not the case itself, but how it pertains to the Brothers Winchester. (I know I consistently repeat myself on that note, but it's important to reinforce what makes this show something more than it appears.)
This was all about Sam and his realization that the current war is not going well. If Lilith is more than halfway to her goal (and almost exactly halfway through the season, of course), and the angels are losing the battle to keep the seals from opening, then Sam has a pretty damn good reason to be worried about the future. And unlike Dean, who has always embraced the manly sacrifice side of Hunting, Sam doesn't want the only option to be "fight 'till we can't".
And that is a new and compelling form of temptation, above and beyond everything else that Ruby has tossed his way. More than that, it's precisely the sort of temptation that never, ever ends well in this kind of story. There's always a way to win the war, once and for all, if only this one price is paid in the process. And that price, it appears, will be Sam's willing embrace of the dark side.
It's been a long time coming, and I'm not sure this particular experience should have been necessary to that decision. Sam has had plenty of chances and reasons to embrace his inner darkness, and he's already taken several steps in that direction during Dean's time in hell. So I view this more of a resumption.
Sam and Ruby were dancing around exactly what it was they would need to do for Sam to gain enough power to take down Lilith. It was enough that I felt like I was forgetting some detail from earlier in the season. Was it Sam's clandestine exorcising, or was it sleeping with Ruby? Both are disturbing and fun, and both will cause Dean to have a fit when he inevitably finds out.
Speaking of Dean (and not of his hilarious encounter with Chief), this seems to tie into the reason why he was chosen to return from Hell. The angels are not going to be happy with Sam at all, and they may decide that Dean has failed at keeping Sam in line. Dean may be forced to choose between supporting his brother and stopping him. That's hardly new speculation, but it has been a long time coming.