Well I gotta tell you this, Supernatural started out normal, basically only demons and unsolved mysteries and all, then those 3 past seasons, it was all about like Big things... God, angels, contracts and breaking them 0_0 , but I Loved the series, and the Finale was pretty good IMO, it tried to explain what was happening this whole year XD
It was weird. The last part of the season finale. Angels and human souls are easily killed in Purgatory, BUT Dean is one of the effin main characters, so I have no worries. Sam would most probably do something stupid just to pull out his bro and Cas outta there in the next season.