A few more details to add to yours (some duplicated):
CONTROLS:
● Wii Remote
● Wii Remote + Nunchuk
● Classic controller
● GameCube controller
● Controller chosen is automatically detected
● Records saved with a icon indicating which control method was used
GAME MODES
● Grand Prix mode has 50, 100 and 150cc divisions
● 50cc is kart only; 100cc is bike only; 150cc is a mix of both
COURSES
● 16 classic courses including Peach Beach, Waluigi Stadium, Yoshi Falls, Delfino Square, Mario Raceway, Sherbet Land, Shy Guy Beach and Ghost Valley 2
● 16 new courses including Luigi Circuit, Moo Moo Meadows, Mushroom Gorge, Toad's Factory, Mario Circuit, Coconut Mall, DK Summit, and Wario's Gold Mine
● Classic courses updated to fit new engine but retain their classic look, i.e. Mode 7 style for the SNES tracks
CHARACTERS, VEHICLES & RACING
● Baby Mario, Baby Peach, Toad, Koopa, Mario, Luigi, Yoshi, Princess Peach, Wario, Waluigi, Donkey Kong, and Bowser
● Suspect there may be more characters, including Mii racers
● Each character has six vehicles available from the start: three karts and three motorbikes
● 12 racers per race
● Bikes are slower than karts, but this is balanced by being easier to boost using wheelies
● Kart boosting through powerslides. Hold a slide for as long as possible, then release to boost.
● Drafting included
● Tricks included - flick the controller at the peak of a jump to perform a trick and gain a speed boost on landing.
● Classic powerups return - green & red shells, mushrooms, banana peel, Bullet Bill powerup etc.
● New powerups include a cloud that must be passed from player to player before it shoots lightning and shrinks you, and a POW block that appears over your racer and must quickly be destroyed by jumping into it.
ONLINE & STATS
● 12 player online
● Two players can play online on the same machine
● Mario Kart Channel to download records, ghosts, tournaments and weekly challenges, among others
● Comprehensive stat-tracking - race and battle count, distance travelled, number of tricks, WFC wins/losses, tournaments played, how many times you've hit/been hit etc.