I think the design and singing were too little to complain about..
We are talking about a 2d-platformer here, not CoD, so for quality such as this, shouldn't have any criticism.
I give it a 10. And the singing wouldn't bother kids which was what the game's main audience consisted of.
Of course someone more older may not agree with it, but yeah overall quality is superb. There should be a different
system used for scoring different games such as this platformer. Platformer vs other platformers if that wasn't done.
The game reminds me of being a kid which reminds me of when I played my first Rayman game as a kid. It's fun to be a kid.