I thought I'd just share my two cents on all the music in the game:
Beach: In my opinion this song is too repetitive, it needs at least one break in it. And also, I think it's quite cheesy how on the last lap the pitch goes up.
Canyon: Great song, it suits the track well.
City: I like this one very much.

I have great memories playing tracks with this song in it.
Crescentcrossing/Lighthouse: It suits Crescent Crossing very well. It adds to the eerieness of the track.
Fortmagma: This one is pretty average, I've never been a great fan of rock music, but that's just my opinion.
Islandtrack/Olivermath: I don't think chiptune music fits in with this game. Although this song did go quite nicely with Oliver's Math Class, I think that it doesn't suit the Island track. The Beach music would probably fit this track better.
Jungle: Very nice.
Mines:A nice little tune here.
Racetrack: Good music here, it makes the track more exciting.
Sandtrack: Another good piece of music that suits the track well.
Secretgarden: One of my favourites. If only DJ Helium could compose some more music for the game, his compositions are the best.
Skyline: Average. The music is too simple.
Snowmountain: Another great composition by Krobonil. This piece of music sounds quite cute.
Snowtuxpeak: Why does this song have vocals? It's supposed to be just background music.
Startrack: Perfect. Suits the track really well.
Tuxtollway: Another amazing piece. Suits the track well.
XR591: This has always been my favourite track, and I also think this track has the best music.
