The Walking Dead was probably the first drama I got into back when it premiered, did not watch many tv shows pre-2010, but I stopped after Season 3 because by then I had caught onto shows like Breaking Bad, Game of Thrones, Sherlock, and now shows like Fargo, and Better Call Saul have recently started. These shows are acted and written better than TWD period. I guess as viewers we have become spoiled with how good television has gotten and TWD just does not hold up against the shows I mentioned.
Now I am not here to just bash TWD. I see why it has its fan base, AMC does a good job at promoting it during Halloween period every year and it is the only show that has anything to do with zombies, besides FTWD. The fact that it has great viewing numbers is not surprising. As mindless entertainment I can see people enjoying the show.