its a little slow but very well done. I haven't gotten that far yet so this may already be, but it could use some kind of enemies walking around you need to kill 'Mario still'.
it would be SO much better if the air didn't just come from random areas and actually followed the road because they're the only ones that kill me because i refuse to waste a bunch of $ randomly scattering frickin' air unit all around the screen!
the first time i played this (i now wish it was when the badges were out) in the 'avoid green balls', and 3 green balls where grouped together AND I COULDN'T LOSE! I could've gotten up to X 20 if i hadn't gotten bored