I don't get how your examples are similar at all. On Mad Men, lots of stuff happens at a leisurely but not frustrating pace but it adds up to zip. Breaking Bad is fast-paced and action-packed and the plotline is definitely going somewhere.
Mad Men is boring because the characters are idiots/grotesque and I don't care if they live or die, and I don't see any progression to the plotlines. Breaking Bad is engaging because the characters interest me and the plotline is progressing at about the right pace.
Shows can take years to evolve their plotlines and still be fantastic. Take Dexter for instance. Between S1 and S4, there has been significant progression in the character. But I guess you could bitch that it's taken four years to push this guy only part-ways along his (presumed) character arc and it could take two more to conclude it.
The progression has been so slow that it was only after I re-watched the S1 DVDs that I realized how much he'd changed. They did it that way because that kind of slowness is realistic. People don't change overnight.