The starting credit was beautiful. It actually tells us the road that the boys have been through to the point after Dean busts out of Hell. Generally, the whole summary throughout all the seasons.
What I didn't really expect [sorta] was that Azazel [YED] has been all along - Lucifer's son. Azazel went to 'visit' his dad at St Mary's Convent to ask his father on how he could set his father free - Lilith.
Sam was beginning to think that his brother was right about him being a monster. But he still went on with trying to stop Lilith from breaking the seal with Ruby's 'help'.
Dean and Bobby got into an argument on Dean being stubborn to bring his brother back - leading Bobby to lose his temper. Which is surprising for me to see because all these time, I have NEVER seen Bobby lose his patience once.
Dean ended up in a 'green place', with Castiel and Zach there. They had a talk on the final seal and it is where Dean learn the real truth in everything. He even learn about the lies the angel had told him.
With Lilith's personal chef in the trunk of the car, Sam and Ruby head on to the convent, to try to stop Lilith.
While that has been going on, Dean tries to persuade Cas to take him to see his brother. Cas was reluctant at first but after awhile, he gave into Dean. That got me smiling somehow to see that he actually believed in Dean enough for him to sacrifice his angel orders to help Dean.
In the end, the final seal was still broken and Lucifer is rising.
It's an amazing episode and the best one - by far. Now I would have to wait for a very long time for the next season to be out. There are so many questions lingering in my mind. Questions like "Will Cas be okay or will he be punished by the archangels?" Or would Sam be Lucifer's vessel?
With those questions in mind, I'm sure it'll stay in my mind till the next season is out.
All in all, great way for end Season Four. Kudos to that! -waits patiently for Season Five-