Too simple for its own good. The graphics look appealing due to having a nice, thick outline, which is the same reason people love the LocoRoco graphics. However, even with the simplicity I think it still could have had more, especially for the menus and such, as that wouldn't have interrupted the gameplay at all.
The music sounds great, but could have used some better sound effects.
As for the gameplay, I have to say it's a little annoying how boring and uninvolved it is. It's way too easy, and all you do is collect coins. Nothing too special there. The boss battle as kind of nice, but a lot of the levels were obviously the result of someone trying to lengthen the game by giving it something unique. The falling spikes and bomb are a good example of that.