This is one of the best episodes ever produced on Mad Men. The exploration of the depth of the relationship between Peggy and Don was so astoundingly written and beautifully put into dialogue.
The build up of the tension between Peggy and Don through the last two episodes that helped in creating a great blow out between the two characters in Don's Office, was a wonderfully and maticulously-arranged climactic scene. It is rare to see such a truely profound moment so well written and acted on TV these days. This episode was especially perfect for Peggy to shine even more. The more they reveal about her personal life the more it tells us about her true character and why she is the way she is, A strong and a potentially powerful woman in times of high patriarchy.
The other part that makes this episode a classic gem is Don's reaction to the death of his most precious friend in the world. Jon Hamm is an amazing actor, and he will surely win a Golden globe for this performance alone. Every Episode I always think they are going to fall into a cliche, but they always manage to turn the story into the most unlikely direction.