The whole thing's a little choppy, but rather good overall. Nice choice in music. I didn't like that if you missed any coins at the beginning, you couldn't go back to get them.
Also, I found a glitch. In the "Secret Area" where the sign points downwards for swimming, I jumped on the sign and went onto the platform above and to the right, which I swiftly fell off of into nothingness as I walked off the other edge.