In Season 5, it seems to me that the central theme was loneliness. Even in the poster to the left, we notice that the Don with his back to us is alone and the two faceless manequins in the shop window give off the feeling of isolation. Each primary character in the series (with the exception of Cooper whose personal life has never been fully developed on the show) goes through some personal crisis (or crises) which at the heart deal with being completely alone in the world. Whether it is the quintessential loner Don who despite his incredible love for Megan, continues to be alone during most of the show (in bars, meetings, etc he is always shown as outside the group or so it seems). Megan, of course, is alone with her passion to become an actress. Peggy has to face being alone having lost her boyfriend last season and now without moral support of her mentor and strikes out on her own elsewhere. Peter realizes that his marriage is a dead-end (or at least he believes it to be) and has a hopeless affair after which his lover gets lobotomized via electro-shock therapy and although the two people are in the room together in E13, both are incredibly alone. Roger, of course, is alone and filling his emptiness post-Jane with young girls. The ultimate victim of his own solitude is of course Lane. Now being able to confide his troubles in anyone, not being able to pay back an outstanding debt, and rejection from Joan leads to a desperate act and its tragic consequences.
The show had some great moments: the roadtrip of Megan and Don, the new Ginsberg character (I loved him!), the Betty/Henry subplot which I found was well-written, the Betty-Megan war…The final two episodes were perfect closers to the various intrigues carried all season and were written with flair, enticing us to tune into Season 6 in 2013. Mad Men is one of the rare shows that actually gets better with age.