It came out on the 24th here in Australia. About time we get a release before you yanks.

I've played it and I'd have to say its one of the better Mario Karts in recent times. Although I will admit that Mario Kart 64 is still superior when it comes to how the items worked.
For example, the homing red koopa shells would only home in indefinately regardless of where you were on the track if you were in 5th or lower place. If you were in the top 4 you could only get someone with them if they were in line-of-sight. That and the spiny shell used to knock you out but still give you some slight forward momentum which meant if you were almost over the finish line you still won. Compare that to the hair-pulling flying purple shell. Things like that may seem small but they make a big difference.