It's one of my favorite shows of all time. It was always a bit of a hard sell to a lot of my friends since the pacing of the show is really slow to begin with, and then it gets even slower in season 2, so anyone expecting "Big" events to happen in each episode were in for disappointment. That said, my friends who watched and loved it, really loved it.
I loved how the characters would develop and regress depending on what was going on with their life. Sure, it's frustrating whenever Don decides to fix himself and then goes back to having an affair, but the show consistently framed it in such a way that made sense with the character and the narrative. Nothing anyone did felt out of character.
It's a shame that across the eight years the show was eligible, it only received one award for acting (for Jon Hamm and only for his final year eligible too) since the cast was amazing.