Mad Men currently is a winner of 15 Emmy Awards, with three for writing. Breaking Bad is a winner of 10 Emmy Awards with six for acting. Both are praiseworthy, but The Walking Dead is equal parts high-caliber acting and high-caliber writing.
What "The Walking Dead" is doing right is staying true to a very bleak premise, while providing a lot of suspense and shocks along the way. Nietsche famous formulation was, "When you look into an abyss, the abyss also looks into you."
Raising a kid with autism and trying so hard to help him or her is about as tough as things get for most people in this life. So one attraction of zombie fiction for me is that, while the worlds they present may have gone to hell, all the children left are perfectly behaved.