1. The opening--very Crowley being Crowley
2. The way Dean yells "Sam" after Crowley hangs up
3. That Rowen survived because Lucifer is arrogant/contemptuous of humans, which also gives us a bit more info on just why old, experienced witches are so difficult to kill
4. Sam and Dean's joint "if" after Crowley's first sales pitch
5. I really like that angels seem to primarily see each other inside their vessels and not their vessels. (The whole "are they wearing vessels inside of heaven?" question is still kind of open, but I will continue to assume it's simply so the show doesn't blow its entire SFX budget and schedule on a couple of expositional scenes)
6. Discussion of why Cas is a strong vessel for Lucifer (for all those folks who were complaining about that)
7. Amara really showing her stuff--some cool effects there
8. The fake owl on the duct-work in the rooftop scene with the Winchesters and Crowley
9. Gosh there are some gorgeous visuals
10. The Lucifer/Amara showdown shows how completely out of their weight class Sam and Dean are--it feels desperate in a different kind of way then season 5 did
11. Sam and Dean bowling with beer bottles on the map table--and the way they keep swapping sides in their disagreements, episode to episode: each one keeps convincing the other of their position, because they're both so open to the other's opinion. It winds up being a bit circular to the audience, but it shows just how crazy-strong and close their relationship is this season. (Yes, that's technically two things; I don't care)
BTW, because I've seen this treated by some people as a canon-error, I'm pretty sure when Amara calls Lucifer God's "first son", she means in preference/love, not "eldest/oldest".
