This episode does a really good job of balancing the principle elements of the show. We get a compelling case of the week with the Croatoan virus; the case works as both set-up and payoff for various elements of the mythos. We get some brotherly melodrama both because Dean dealing with the promise he made John and the scene of Dean admitting he is tired. The show has some funny bits that stand out. And the episode plays out as a riff on the zombie doomsday. Overall this is what the show tries to be. Croatoan is tight.