The episode started with what some people thought Dean would never do in a million years, saying yes to Micheal. From the beginning Dean was against the plan that the Angels had for him, to be Micheal's sword. He had us all convinced all the way to the end that he was going to say yes, but that eventually turned into him slaying Zachariah. I'm not saying that Dean will never say yes to Micheal, but we do now know that he has the passion too do so, and that he's willing to save the lives of billions in exchange for his own life.
This episode did have some, not a lot, but just enough comedy in it to call it a true Supernatural Episode. Toward the beginning when Adam was brought back to Bobby's house and they discovered what the angels were up too, Cass explained how their moving on from Dean by using Adam as a vessel instead, Dean turns around and says "Blow me Cass". Now that got me laughing. Also when Dean told Adam that they were working on the "Power of love" as a solution to kill the devil, that was a nice comment that got people laughing.
Overall, I enjoyed the episode. There were a lot of plot twisters, characters that came back from the dead, and the most important moment that i think happened, the biggest dick of the season was killed.