Players control the board by standing with their feet parallel to the screen, like they're on a snowboard. Bending at the waist makes the board turn. This is honestly what takes the most amount of time to perfect because my body naturally wanted me to turn like I was riding a snowboard. Players can activate boost by kicking their leg out like they're on a skateboard. Crouching and jumping straight into the air makes the rider do tricks off the jumps. Each weapon has a specific motion control as well. The bomb is thrown like a football, the bowling ball is bowled, etc. Rings are scattered on the course, and as players collect them their board will level up, increasing in speed as the race progresses. Getting hit with weapons causes players to lose some rings, which can level down the board.
Sonic Free Riders also features bikes, which players control by standing facing the screen and holding their arms out like they're gripping handlebars. Kicking out still activates boost and all the items control the same. I found the bikes to be tiring on my arms, but on the plus side I was totally able to play the game while sitting on a stool.
The motion controls all worked just fine as long as I was doing exactly what I needed to. Simple things like not throwing with the same arm that the on screen character was using would cause it not to work. It was a bit frustrating at first, like having a game tell me I didn't press the X button in quite the right way. But once I got into the groove and retrained myself to play the game the way it was telling me to, it all became a lot more fluid and easy. I've played the previous Sonic Riders games, and this is definitely the most fun I've had with the series. It brought back fond memories of playing Top Skater in the arcades.
Free Riders' story mode is broken up in a variety of missions. Each team has their own set of missions, though they're all very similar to each other. They're sort of extended tutorials. Players learn the various skills the rider has before building up to full races. It's broken up in a way that works for this game. Instead of just doing race after race I got to do more specific challenges between them, like collecting rings, or using the special moves.
One area where the motion controls don't work is the menu. Trying to maneuver through its screens is far more difficult than it needs to be. Thankfully, Free Riders' voice commands work surprisingly well. Players simply say "Free Race" to select that. It's fine for most parts of the menu (though memorizing the names of all the courses, riders, and gear parts is a bit much to ask).
As players progress through the missions they earn some new boards and gear parts, and also earn rings which can be used to purchase additional items. The boards all have their strengths and weaknesses, but it's the gear parts which make Sonic Free Riders interesting. Each board has two slots, and whichever side of the board is facing forward is the gear part that's activated. These can be anything from skills that let the player grind on rails to a shield that pulls in rings to a power-up that gives the player big air on jumps. Choosing which gear part to use changed how I played the game.
Each of the 16 tracks has numerous shortcuts and secrets, so there are multiple strategies to perfect. They're all well designed, they feel unique, and they're all large and vibrant. There's a lot going on onscreen, from dolphins jumping over the track to temples collapsing, and the game runs beautifully without any slowdown.
All these strategies come into play in the multiplayer mode. Whether it's local split screen or online, players need to know these tracks and have a strategy in mind if they want to win. The co-op modes are even more dependent on players knowing the game well. Tag mode, which links two player's board together, is an interesting synchronized exercise. If both players are actually in sync they can pull off some cool moves and the mode is really satisfying. If they aren't, then it feels like a bumbling mess, with the characters bumping into each other and getting their butts kicked.

Sonic Free Riders is, ultimately, a fairly standard racer that works well for Kinect. Pretending that you're on a hoverboard is actually a lot of fun. The tracks are well designed, the level of board customization makes the game more robust than many racers, and the numerous multiplayer modes keep the game entertaining past the main missions. It's not amazing, but it's definitely one of the games you should get to round out your Kinect collection.

This is a copy/paste review of this review from IGN:  http://www.ign.com/articles/2010/11/01/sonic-free-riders-kinect-review
Not only is plagarism against the rules, but it is against the law.  Therefore, I am closing it.  If you have any questions, feel free to PM me.
[Closed]