Art is really good. I was also really surprised when the camera moved in combat I thought it was fully 2d.
In the current state the overworld movement seems superfluous but I'm guessing you have more plans for it that just weren't ready for this demo.
I will say deciding when to heal is kinda awkward since I the main battle screen only displays current health and not max health.
Also the fact that this game has press turn wasn't clear at all. When I was playing I didn't really understand how many turns I was getting and why my guys got to make multiple moves per turn until I went to go write this comment and read it in your changelog below. Obviously a tutorial could help but I think having sound effects and more explicit UI would be a better solution to make the mechanic intuitive.
Really cool Demo, I'll be keeping my eyes on this one!