This game caught my eye and I finally had the chance to play it at a friend's house a few days ago.
My thoughts on it are that it is a fun game but it gets boring very quickly. I'd call this game a 'rental' title, although video game rentals are kind of a thing of the past. The problem with the game is that there's so few types of courses / minigames that it gets stale remarkably fast. Also, random luck has a LOT to do with it. On 'race' types of courses, if you start in the front you have a much better chance of qualifying or even winning than if you start in the back, and that's completely random. Also, the controls leave a lot to be desired. You basically just run and steer 90% of the time. You can jump, but the jump mechanics aren't very satisfying and there's this annoying little delay between pushing the button and actually jumping. Aside from that all you can really do in the game is dive forward, which is sometimes useful, and you can also press a shoulder button to grab onto someone, or an object. You can't 'attack' anyone per se, and in many of the game modes it's not worth messing around with anyone else anyway.
Is it initially fun? Yes. Is the art style cool? Yes. Is the game active? Yes. The sound department is lacking though. The music is boring and unremarkable and the sound effects are forgettable and bland. Also, there's really no 'end game' to it at all. If you win a certain amount of times you can get enough crowns to unlock special outfits but who cares lol. I definitely wouldn't pay full price for it. Some people might have a blast playing it but I know that for me I'd get super bored after a week. You can pretty much experience all the game has to offer in 1-2 days.