One thing I want to say about the story is how Ardyn had potential to be one of the franchise's best villains, one of the best villains in any RPG. His backstory, motivations, and goal set him apart, and I like how he managed to one-up Kefka by not only succeeding up to the final climax, but arguably netting himself a win-win situation in the end. He got his revenge on the Oracles and Lucian kings by ending both of their bloodlines, and was finally freed from the curse of immortality. He even achieved what he had been chosen to do in the first place, ridding the world of daemons.
Too bad his cool personality faded in chapter 13, and he just started acting like another evil maniac. The final battle was also a letdown with that ridiculously anti-climactic super-Armiger-mode ability (which was also a waste of Leviathan's set piece). Overall, the story was just too disjointed and incomplete to do Ardyn justice. Maybe the feature film would help with that, since it was included with my game, but I don't know when I'll find an opportunity to watch it.
Also, blinding Ignis for no apparent reason just to reveal how it happened in his DLC episode (presumably) was a dick move by Square Enix.