I felt it had great level design, and the mechanic opened itself up to a lot of interesting puzzles, however I think the controls needed some refining. Some issue I had were;
- - It took me a while to realize that I had to keep z held down in order to bounce off slimes, this should probably be mentioned somewhere because before I couldn't tell why sometimes I would bounce low and sometimes I would bounce high.
- - At times I would press x to choose an ability in the air and when I press z to do it I found that I was using a different ability than the one I selected. Maybe having a different button for the action and selection, or a check in code, to only change the selected ability if the window is still open after .5f of a second, to reduce the chance of this happening.
- - When getting a reset coin, if pressing Z would let you use the last ability without having to reselect it.
These could have just been me, but I feel if these inputs were polished up it would help reduce the difficulty curve and some frustration that can be caused by deaths that are due to unintended inputs rather than skill (though i'll be honest, I would still probably die a lot). I'll be uploading a video of my playthrough of some of this game soon, so that might make it clearer, hope this feedback is helpful.