Really fun! I beat the whole game.
I think the game is excellently made and designed! All the numbers and breakpoints make sense and play well together.
I will say that level 5 was a crazy difficulty spike for me because of something I felt was not communicated clearly.
Spoiler below:
I did not know that a targeted ability (like the heal effect) could be cancelled with right-click. I read a comment that hinted at it, which finally let me solve level 5, but it was pretty frustrating.