Pretty neat idea though a little more polish would've helped a lot.
The game was too easy without the need for the slowmo for a good chunk of gametime and the bug where cubes spawned during slowmo don't slow down too harmed the experience a lot though I'm sure these will be fixed. Personally, I would've preferred that your character moves during the slowmo and that the spacebar be held rather than toggled(though this could be extremely subjective).
I think the idea was pretty cool though and would love to play a more polished version of this! Hope you develop it further and I wish you the best of luck if you do.