I can't think of much to say about this that I didn't say in my review of Season 1. If there's a difference, it's that the behavioural period details (misogyny, casual violence to children, ubiquitous cigarette smoke etc.) aren't rammed down our throats as much - a good thing.
As in Season 1, the acting is a joy to watch. There is not a weak link. I particularly liked Mark Moses as Duck Phillips, a character who'll be familiar to many who've worked in the private sector: the ambitious loser who won't settle for anything less than senior management, his career portfolio a catalogue of misjudgments.
I didn't give this 5 stars because beneath the style, there is some variability in the quality of the writing; while in most episodes it is excellent, in a couple of them the dialogue is a little predictable and the plotting contrived. I also observed numerous verbal anachronisms (e.g. "Your job is to manage people's expectations" - sorry, but no way did people talk like that in the 60s!). You may say this doesn't matter, but given the obsessive attention to period detail in the sets, I feel it's a valid criticism.
There is always a danger with long serials that they end up somewhat "soapy", with characters changing to fit plots and provisional climaxes gradually undermining the dramatic tension. I'm not saying this has happened with Mad Men, but I'm starting to wonder if there's any real answer to the question, "What is Don Draper like"? The promise of a resolution to his identity crisis still hangs in the air, and I don't feel it can be put off indefinitely.
Don't get me wrong, this is an excellent drama, with substance behind the style. As I said above, the acting is wonderfully subtle, and the writing often is too; where it's not, the acting and the direction still carry it.