I have to hand it to the producers, writers and director. While I've enjoyed the show since it's beginning, the first season had some bad acting (the played-out abusive husband trope, for example) and even the Governor in season 3-4 was a bit too much of a typically "charismatic" TV character. They tried to give him some depth, which was somewhat successful, but I still found him a little boring.
There's nothing boring about Negan. He's fearful, terrifying, disturbing and yet admirable. While it's easy to predict that Rick will eventually keep his promise to kill him, he's a genuine villain who will keep viewers glued to their screens (at least if they can stomach this season).
This show has definitely matured over time.
I wish we could have just one season that focused on civilization building instead of interpersonal and intercommunity conflict. We were almost there in season 5, but then new conflicts and challenges were introduced.