Just finished the demo with the Tank character and I suppose I have a few concerns. Obviously the art is great as always and the setting seems really cool, these are just potential issues to perhaps head off at the start.
The biggest one is the scope. 3 characters all with at least some unique dialogue, completely unique portraits/sprite sets along with ability sets as well. It's going to be a huge amount of work compared to your other projects. It all looks awesome and I am keen for it but it just seems like a lot. I would perhaps suggest picking one character to be the main focus and then building from there perhaps?
Another is the music. I would suggest lowering it in volume or simply having the downloaded settings at something other than 100%. It was exceptionally loud when I first booted up the game but it seems thematic.
The combat seems fine for now. The issue of balance might come up later. How hard are fights meant to be in general? What about when taking into account the other characters? Does a fight require say a status ailment one or two of the characters can't access. Stuff like that.