If you won't bother to put up a site for the game, then I will :P.
http://www.sega.com/gamesite/sonicriderszg/
They also have Un-Gravitify on there, which I agree is great. Much better than any track on the first Riders. The only two songs I liked from that were the Egg/Ice Factory theme and "Catch Me If You Can" (which is supposed to make a return appearence as the Babylon Rogue's theme song).
I still love the first Sonic Riders quite dearly, and never found too much of a problem with it besides the turbulence (which would always catch me in it and for the most part force me in the direction I don't want to go/away from a shortcut/off the track if the opponent fell), the jumping slowing your speed drastically, and the
RIDICULOUS AI difficulty at first. Oh, and Jet's voice was pretty awful too. Other than that, it was a very solid, very fun racer. I would go as far to say it was more fun than Mario Kart Double Dash, though it lacked alot of its polish, and a huge "race-on-every-track-in-the-game" GP.
Zero Gravity looks like it made some much-needed improvements: they really pushed the speed up this time; boards no longer need refueling which means the air gravity gauge can be used much more freely, Rail grinding is
much faster, jumping no longer kills your momentum, the maps are no longer so cramped and complex that determining positions is impossible (looking at you Egg/Ice Factory), and the art direction and level design is wonderfully surrealistic and more complex.
This'll pretty much be a must-buy for me. I just really hope the character animation for the start of the races isn't typically so...awkward. Tails just looks downright possessed in one of the IGN videos.