Challenge is never simply there to convey new ideas. First you introduce an idea, then you demand that the concept has been internalised. If you don't escalate then you've thrown an idea at the player and they may have lucked out getting past it.
There's shortcuts to bypass the hard bits on the backtracking, perhaps they aren't telegraphed well enough.
Criticism is welcome but criticism is far better when you complain about specifics and what to do about them. Because then I'd be able to work on a directors cut incorporating everyone's feedback. "It's got no music" or "this is too hard" is unfortunately something I can't respond to. I'm not a musician and to me the game is fairly easy (and I'm really bad at most games).