Just because it's made by Nintendo doesn't mean it's fantastic. This game is the case in point.
There is nothing terrible about this game, but there is nothing great about it either. The controls are so simple my 3 year old can play it, and he doesn't come last on Jet Race like he does with Mario Kart.
Graphics are ok, weapons are ok, courses are uninspired, but the whole thing is lacking in that 'wow' factor. It's too shallow to have any replay value, so you won't be playing it much after you've completed it. Kids will love it though.
If you were expecting a high quality game like Diddy Kong Racing or Mario Kart, you will be disappointed. If you wanted a fairly fun, simple racer to whip out at parties then by all means give it a try.