You're in for a treat. It's only got better and better after every full rewatch I've done. I think I'm at four or five now, haha
Lol, each subsequent season is better than the prior one! It's the only show I think I've seen that gets better and better up until a perfect ending.
Season Six dips a bit but overall it does get better over time. Getting out of the Draper house and the old office into the brighter surroundings makes everything look nicer and the character interactions more interesting. It ends up symbolizing the evolution of the Sixties in its own way.