The concept is pretty cool! I'm glad you got this out there and made it! Now you can add some more levels, or section the levels somehow and made it world-based, or whatever! There are lots of directions to take this, given the good foundation you've lain for it.
Personally, I like less floaty jumps, and my gut reaction was that it wasn't clear enough that I was gaining time, but after ten whole seconds of play I was very on board with the experience and thought that it all added to the feeling of recognizing what to do in a short time-frame (Warioware-esque?? Perpahs that's the direction!).
Dunno if it was on purpose, but sound started off by default for me (I guess I just assumed it didn't have sound because it was a Jam entry and I tunnel-visioned on the gameplay, but my point is that it really adds to the experience, so maybe take it as a sign that you might want to emphasize it more or start off with sound on).