This game is really good! (even played it to completion :) ) The levels were tricky at times and I definitely had to rack my brain to solve them which made the gameplay fun. I loved the game, but I do have a few minor and nitpicky criticisms:
1. Showing the points required to finish a level at the start would be great!
2. Having the time translate into a predictable number was be something that I wished for when playing the game. For example, 15 seconds could translate into 150 points. This way players can do a rough calculation of how much time they need to pass the level.
3. As others have mentioned, instant restarts would be convenient, but you already planned to implement that : )
Absolutely fantastic game and I wish that there were more levels! I hope that I'll become as talented as you someday!