Not sure if this is the kind of feedback you're looking for, but I'd like to see difficulty ramped up in a way that doesn't require various forms of grinding.
I guess I'd like to see enemies hitting with more status effects, or doing strange things that the player needs to notice and react to. Kind of vague advice, but I think it's a lot more fun than running into a boss who can one shot your party and then spending 30 minutes bringing your characters to a state where they can survive. Especially in a game that is encouraging you to run from most encounters.
I felt the pacing of the difficulty curve has been pretty solid thus far, but I wouldn't mind things going up a little bit as the game goes on. There may be some room to increase difficulty outside of the battle screen as well.
And here's a random thought, but how about rewarding players with exp/AP for getting through an area without getting into X number of battles? Obviously not including the enemies that block passages, and never making it 0 to guard against bad luck with the random movement of enemies.