Well it's very VVVVVV, so the idea isn't terribly original. (I've never played Gravity Duck 1 so I'm not sure if it was done before) The execution however, I think is pretty great. I like the graphic style and the music fits well. The level design is pretty good too.
I would've given it a 4 if I didn't have the click the continue button every time I finish a level. I know it's a fairly minor thing but I did find it a little annoying. Overall though, a fun little game.