The pure funnest game I have played since... ever.
My only true complaint is that the game is a bit too easy, and I only really reached challenging points by playing everything the game offers, rather than the main quest.
Wii has had a few great games like Metroid Prime 3 and Twilight Princess, but both pale in comparison to the masterpiece that is Galaxy. If you could only get one game on Wii, you'd have to be out-of-your-mind-crazy to not pick Galaxy. Galaxy is my nomination for GOTY so far.