It's actually a little unfortunate that Nintendo has set the bar so monumentally high in the "kart racing" genre--any casual racing game will inevitably be compared to the Mario Kart franchise and most likely lose. Wacky Karts has everything you'd expect from a retro Mario Kart clone: a variety of "karts" (each driven by different large-headed characters with different speed/acceleration/handling attribute), a campy soundtrack, a grand prix mode, time trials, and a battle mode. The game looks and sounds great, but once you actually start racing it becomes quickly apparent that the polished gameplay just isn't there.
The handling is sluggish but not so bad that you want to throw you controller at the TV. Unfortunately, that's more than I can say for the collision detection. If you hit any sort of stationary object at all, you can basically give up any hope of winning a race. Running into a wall or a tree or any similar obstacle will stop you dead in your tracks, and you'll be forced to painstakingly turn 90 degrees to the side (you can't accelerate into the wall or slide along them to free yourself), drive to the end of the obstacle, painstakingly turn 90 degrees back to the way you want to go, and then continue on your merry way--now most likely dead last in the pack.
I'm not saying the collision has to be perfect in a Kart racing game, but if there's going to be such a drastic penalty for hitting something then there needs to be mechanics in place for recouping that lost time. While the collisions are frustrating, the worst part about Wacky Karts is just how impossible it is to make any sort of leaps in the racing pack. Shaving corners will get you some time back (assuming you don't hit a hazard), but it's not enough to move from 8th to 1st if you don't get a good start (or--heaven forbid--run into something). There are a couple of powerups: the equivalents of green/blue shells, a hole/tar-slick that I imagine works like the banana peels, and a rocket boost. These work okay, but most of them allow you to move up one place at best, which makes the catastrophic recovery impossible.
This ability to recover mid-race is actually what I would consider the defining characteristic of the Mario Kart franchise, and it's omission from Wacky Karts just makes the game feel too deterministic. At 400 points, it's hard to recommend an Indie Game that doesn't seriously "wow" me. I can't think of any other racing games this casual on the platform, so if you've got little ones WK might be a pretty decent purchase if the price comes down. Until then, steer clear. Get it? Steer... clear.