It's required listening for people with souls, and a nice way to look forward to the game without spoiling it if you're not lucky enough to live in North America, where it was released yesterday. Europeans will have to wait until 11th June to pick it up.
Frankly, the entire soundtrack is brilliant, but if you just want a taster, we suggest you try out the themes for Sky Station Galaxy 1, Puzzle Plank Galaxy and Slipsand Galaxy. Listen to those without grinning. Go on.
Then go read our 10/10 Super Mario Galaxy 2 review and grin some more.