Only critic I have is that getting into purgatory, into hell and back again seemed a little too easy.
The place felt smaller than Mordor in Peter Jackson's theatrical cut of Return of the King.
Things are always way too easy on Supernatural. Look how easy it was to convince the kids that their hunter mentor was up to no good. They just happen to walk in on him and a vampire as they're about to kill Sam.
How many times have the bad guys used their powers to simply push Sam and Dean against the wall rather than snap their necks instantly?