I got the game at a midnight launch. It's quite a solid entry in the series - the multiplayer aspect totally makes up for the disappointment of Brawls wifi capabilites. The Wii Wheel is really great to use, too - I wouldn't recommend it in a 150cc race, but if you're playing to just have fun, give it a whirl. You may find it better than you thought you would - I know I did.
Some of the maps in the game are the most unique in the series - Warios Gold Mines? Koopa Cape? Mushroom Gorge? Absolutely top-notch. Sure, some of the retro choices are mixed (WHY IS THERE NO ROYAL RACEWAY), but I can live with those. The fact that they brought back classics like DK Mountain and SNES Battle Stage 4 make up for it.
Sure, the rubber-banding of the AI is cheap as ever, and some of the unlockable characters are a bit...uncalled for, but it's a solid kart. Better than the GameCube and N64 iterations, at best; perhaps not as good as Super Mario Kart.