Some(if not all) upside-down gravity levels can easily be beaten by just using what I suppose might be an oversight in development where you can just keep hitting up and down and it makes you fly.
I wish the mouse was equally sensitive horizontally and vertically, and that the horizontal sensitivity wasn't so massive. That and that the cursor is locked in the game screen as you're playing, then you can just make it so if you press a button, it's unlocked until you click the screen again.
As pretty much everyone that's gotten past level 10 thinks, please, for the love of all that is Papa's, shorten the bits where they order things and measure their food/wait quality. It makes it very difficult to multitask when you have to wait 15 valuable seconds for them to give you criticism.
It'd be nice if, on the different instrument pages, you could see a ghost image of what was on the other page(so if there was a line of notes on the other page, you would see them slightly transparent on the current page).
"Immense explosions and fast paced action will make it difficult for you to stop playing."
I quit on the first level, it was that boring and slow. Try ramping up the speed next time.
I hate how physics aren't being rendered on moving gates. My red ball got stuck in level 2 because of that, when it could have just been pushed down like a normal puzzle game.
The Charm spell is supposed to ally enemies with you temporarily, but they don't attack other enemies, even when you fight them. Is that an unfinished spell or is it just supposed to ensure enemies don't attack you for a while?