Really cool demo. I have two suggestions that might make the experience a little bit better.
1) A camera sensitivity option. Camera movement in the demo felt rather slow, as if it had low acceleration, and it made playing the demo a tad annoying, specially when trying to see what stuff I was missing and in the "bazooka-a-mole" minigame. A faster camera might also improve character movement.
2) This one is a nitpick, but I think there's no need for Paint Gal to speak every time we collect a gem, considering how many of those each level will have. Maybe you could have her speak each 10 or 20 gems?
Other than that, the game is great as it is. My favourite thing by far were the fixed camera sections, those were great and helped a lot with the platforming in those specific areas. Several other 3D platformers will just screw you over in those exact situations and you can't see anything.