It is a decent game. Grinding the money is pretty dull as others have said and I feel like you've designed the levels to severely limit how fast you can go and how many tricks you can do - without a jump or boost function the flips have seemed virtually impossible to pull off so far (I haven't played through the whole thing yet). To me it would be more fun to have a bit more balance towards trick-creating downhill-to-ramp moments.
My only real complaint though is that you lose too much fuel while not accelerating. But it is pretty good overall.