Great Game.. Characters are good, karts are good and you can change your mii from medium to large,etc.
You can now play as some new characters never featured in previous mario karts such as Bowser jr, Dry Bowser and more. The good thing is that unlocking the characters is not just a matter of your progress in the game (eg. you beat star cup 50cc and now unlocked bowser jr, but the you beat the very next cup and unlock dry bowser) you may need to beat cups, get star ratings in cups, unlock expert staff data (time trials) or just win 1000 WiFi races.
Now Tracks, The tracks in this game feature tracks with bright colours and very modern graphics, but the game also features a selection of retro cups. which holds races from the Snes (eg. SNES Ghost Valley 2), the GCN (eg Peach Beach), DS (Yoshi Falls), and N64 (sherbet Land).
Online play, The online play in this game is excellent, despite that you can get kicked out of a game for waiting too long, it holds lag free matches against people Worldwide, Continental & Friends.
Though It would seem that you would most likely go to continental races because people in your continent have the same time zone and wont leave the match when it is 3PM at your house but 3AM at theirs, and they have usually had the same experience. I got my game on the first day it came out aswell as about 1000 people in Australia who did the same. So we have had the same experience as each other.