It it's current state I think it's only worth 2.5 stars but you could easily get this to a 4 star game with some simple improvements.
First sound options or at bare minimum a mute button.
More gradual difficulty curve. Think how easy the first few levels of monkey ball were.
It's hard to tell where you are in relation to small platforms sometimes. Most 3d platformers have the player's shaddow straight down to make this easier but there are lots of other ways of going about this, you could even have a topdown minimap.
Camera control using the mouse would be great.
The timing needed to bounce up the walls is pretty tight if you must have it this tight maybe make the tutorial wall shorter. Seems a bit unnessisary too considering it's never needed in the actual game (unless it's on the last level which I haven't unlocked).
The tutorial aught to have checkpoints too because dying straight after that and repeating the section is annoying.
I fell off the level using a jump pad and jumping to the left side on the first level with the flashing red kill barriers. This uncovered 2 problems. Inconsistancy with invisible barriors and it doesn't restart the level like it does when you are killed.
Other than that it would be cool to have more of a reward when you complete a level, particles, more triumpant sound that kind of thing.
Other than that what you've implemented is very solid and I hope you continue to improve it.