Each of your four levels play very differently from each other. So I broke it up to give you feedback.
Yp. 1 Infinite momentum building, please and thank you.
Yp. 2 Very difficult to control, but inventive.
Yp. 3 Controls the best, but I'd appreciate a progress bar. Also, that kill box is junk.
Yp. 4 Weird graphical glitches (spike strips), and if we're going in order of difficulty this is probably the easiest actually.