I enjoyed it degree, but the controls were anoying. Plenty of things I'm used to in other platformers are not here.
You keep all the momentum after releasing the key, can't make tiny jumps by just tapping the jump button, pressing down makes you crouch instantly even if you are still holding left or right and I don't think I used the back jump once.
Personaly, I don't think this is a really bad thing. The game was obviously designed around these controls and changing them would make the game way too easy. I simply sat down, learned the game and got through it without any great issues (Stage 5 and 6 were the hardest. 7 was suprisingly easy compared to those), but most people are probably not going to do that, which is a shame.
Few suggestions:
More sound effects for jumping, kicking, hitting the floor and more. The game is too silent,
Try adding shading around floors and walls. I missed the very first platform because I thought it was just a wall decoration since it had no shadows and thus no depth. Something like this should be enough.
I like the artstyle. All animations except for the running were fine. Running animation could be improved.
Adding some kind of speedrun or challenge mode would also be nice.
And that's pretty much it. I enjoyed it, but I don't mind re-learning things. I checked the steam page and most people don't like adapting to something different. Changing the controls would make the game more enjoyable for more people, but you would probably have to rebuild pretty much all the levels from scratch.