I have been rewatching Mad Men on demand for the past few weeks.
It's interesting. The show still works as a low key melodrama, but there is are quite a few things that stand out during a second viewing, particularly having the hindsight benefit of the first.
The first is how inconsistently the Don Draper character is drawn. I mean, he really comes across as a sociopath, and possibly even a psychopath, in early episodes. The first time we really see him connect with someone is during the famous "this never happened" scene with Peggy. It isn't even clear that he loves his own children for the first couple of seasons. Then his character seems to shift, almost overnight, evening out so that he actually has multiple warm and tender moments per season, usually with his children.
It's a very sudden character shift. People do not change this late in life, in my view, so what explains it? Perhaps the divorce with Betty (which is something else that comes very suddenly and seemingly at the wrong time).
Also, consider the Roger character. I like John Slattery and Mad Men would not have been Mad Men without him, but he was really not right for the Roger character, who is consistently drawn as a man at least 20 years older than John Slattery obviously was at the time the show was filmed. John Slattery, frankly, seems like he would have made a better Don than a Roger. But where would that have left Jon Hamm?