And his mother, she was built up and then they both just disappeared. But I noticed before that: the first episode was about Peggy arriving in the agency and the indication was that we would see it from her lens, then for weeks after we saw nothing of her life and she had only a few not very interesting scenes none of the plot from her POV, then it all took off again. Now once again it's all kept a secret. This can be intriguing, but it's also irritating, the viewer should be in on the secrets not played with just by not dealing with them for a few weeks.
There's an imbalance between it being office or domestic based and it is uneven between the two- deliberately so, unconventionally so, but it makes it fickle - the character of Joan who has to be one of the most interesting ones, is only very rarely taken outside the agency, yet she is clearly one of the driving characters etc.
I like it, don't get me wrong, I used to work in an ad agency years ago (not that long ago!). I would just like there to be more rather than less.