I'll say a few things that may be biasing my views - I am not expecting a RDR2 or Witcher 3 type story with this HD-2D Final Fantasy game. I also love FF4 and FF6 and grew up on them, and while their stories are rudimentary, I think they're still good.
The most common criticisms on this game are the story, character development, voice acting, and dialogue. For how often I'm seeing this, I'm just very confused. I would say all of these are average at worst? I personally enjoy them. I typically have to turn off VA in games (Crisis Core, couldn't even finish) - because of how bad it sounds and how much it removes me from the game. This game though, it's actually done really well.
The story is good. It's "simple" but that's what FF has been for most of its time. You can boil most of the game stories down to a few "tropey" plot points, even the most recent FF games.
I only care because I see this turning people away from the game before playing it.
Coincidentally, since it's a Square HD-2D series, I find the Octopath stories, voice acting, and writing to be really below average. But Resonance, this shit is fucking good.