I.... love.... this.... game....
Graphics/Visuals: Outstanding, they really push the wii's limits to what it can do. It runs very smoothly in 60 FPS. It is very bright and colorful and the artwork in some of the Galaxies and the hub world are absolutely amazing. I would have to say some of the best art (if not, the best) in a video game to date.
Gameplay: Very fun and just right, it's not too hard and not too easy. It's what you'd expect from a 3d Mario platformer, but with a little kick. Mario controls nice and smoothly and using the pointer is cool and somewhat intuitive. Multi player is fun with someone else if they're willing to use the pointer by itself. There's many bosses and that just adds to the game's fun.
Sound: To me, this was the biggest treat. All the music is beautifully orchestrated. You walk into a galaxy and do not know what kind of music to expect, but every time I was surprised and I was very happy with what I had to hear.