I FINALLY WATCHED THIS, SO... HERE IT GOES
I have to say, it didn't surprise me a lot, like, it isn't mind-blowing or anything like that.
But it is the most beautiful finale I have ever witnessed. Every character conclusion was goated, and it fits so well with all the plots. 
The cinematography was perfect.
The acting was sublime.
The dialogue was a masterpiece.
Everything is just BEAUTIFUL, and it enters in my top 5 finales. (I have to start doing lists...)
I love that Peggy, Pete, and Roger have what they wanted and are happy now.
Joan also got what she was aspiring to, and even tho it cost her a relationship, I think that in the end, she was proud of herself.
Betty and Sally are the only ones who have a sad conclusion, Betty for obvious reasons, and Sally because she has to deal with all the family trouble and now has to take care of her brothers.
Don, man... what a ride!!!
His conclusion is amazing, and he finally gets some happiness and understands his problem with social relationships (or at least, that's what I imagine he ends up doing)... And when he comes back, I understand that he does that famous commercial of Coke, right???
Well, EVERYTHING BEAUTIFUL AND FITTING.

Extra Comment: I love that scene where Stephanie goes away, and Don goes to reception and asks if she left and says, "People just come and go, and never say goodbye" in an angry way, and the receptionist tells him "People are free to come and go whenever they want". I think that scene perfectly represents Don's feelings and how society and people sometimes work.
BEAUTIFUL FINALE.
(Sorry for the long yap)

Specials

Season 1

Season 2