Awesome game,
But improvements needed. You should've added a bit more to the game itself. Make it possible to jump all the time, and some obstacles that can cause a wipeout, it NEEDS a left and right axis to it, so it involves more skill.
THe customization feature is nice, but some effects need work. Light snow was good, but heavy snow was annoying, I expected a rapid moving snow sequence like a blizzard. Night setting needed work, you should've made more of a vibrant dark, it looked like you put a low alpha black screen through the damn thing. And what about a charachter and board selection? That'd be great.
The tracks from the sonic games were all great, but there should've been at least one old school track, I'd say find the snow level track from sonic 3 and stick it in there, because sonic 3 music from the sega genesis is awesome. I'd say eliminate some of the less cool ones, use the saved filesize to add more quality to some of the cooler tracks, they need a more dramatic high quality feel.
All in all I hope you make a V.2 revamped game, fix the customization stuff a bit, add some features I suggested, etc. I look forward to it.