A highly addictive game: it is beautiful in so many ways, from the graphics, to music, to developer interaction (always exciting to see you in a race, Fex), to the joy of just beating your own best times.
Given how many people complain about the mine levels, perhaps it would be possible to add a "tutorial" (like how at the very beginning there is one on normal racing), and provide the option to repeat those as a player wishes? I suspect that part of the reason people dislike mining levels is simply that they don't understand how awesome they are.