Sonic Free Riders is purely Sonic. Bright, vibrant colors; inventive locales; up-tempo music - it's right in step with everything players have come to expect from the franchise. Races are introduced with short story sequences that attempt to tell some sort of over-arching story, mainly through the use of trash-talk between teams of Sonic characters. Dialogue sounds okay considering the source, but I spent more time resting and catching my breath between rounds than actually paying attention to what anyone had to say. Still, they look good for what they are.
The game's real star is the tracks. Although teeming with predictable themes (the "lava area", the "ice area"...), each offers some visual set piece, many of which indicate some sort of short cut through the level. In one area, you'll ride atop the spine of a dinosaur fossil, while in another you'll crash through sheets of ice (you're even required to make a punching motion to do so).
It's also pretty cool to watch character's mimic your real-life motions. The cool-factor begins to crumble once you start to play, but the presentation is enough to actually make you think about coming back.