I finally got to start playing this over the weekend. It's a blast, though, thus far, it seems to be a little easier to get gold medals and collect all the items than I would have expected. Still, it's just fun to see the craftsmanship in the level design, and the soundtrack is very pleasant. Love it, and I love the 2D platforming renaissance on the Wii in general.
I was hoping to get my wife to play co-op with me; normally, she would, but she's surprisingly disinterested in this game. Maybe that will change.