I've had the 3DS since release and after much waiting, have finally received this game! Mario Kart 7 and Super Mario 3D Land have brought the 3DS to life instead of those not so good 3rd party games.
Mario Kart 7 is an AMAZING game, it's bright, vibrant and will have your mouth wide open when you race on your first course. The graphics aren't as good as the Wii's but the 3DS produces quality lighting and shading effects which make it look much better than on Mario Kart Wii.
The glider is a nice way to cruise through the course and you'll feel like a fan boy remembering all the GameCube, Wii, N64 and SNES courses. The music on this game is also very appealing, has me turning my volume way up.
With every game like this though, I believe that playing with other people (friends and online) is what pushes the game to it's peak. With a Mario game you never know when a blue shell will come and hit you right at the finish line or a lightning bolt striking you down from your glider at the worst possible moment and this adds to the excitement... As well as frustration when you know victory was in your almighty grasp!
The only downside I'd say is that there's a lack of characters. I'd of loved to see the baby characters, Dry Bones, Toadette, Diddy Kong etc. But it makes up for it in a sense with new characters and your own Mii Character which looks far better than the Mii racer on Mario Kart Wii, so treat yourself, siblings or children for Christmas.
Get gliding, diving and screaming; enjoy all the courses, new and old, but for those that fear Rainbow Road beware, there are two Rainbow Roads in this game - MWUHAHAHAHA.