The art is amazing, especially that parallax gives it a polished style. The game play is simple but fun.
The only thing I think is annoying a little bit, is that the game seems to force you to defeat all enemies before allowing you to proceed to the next level as I found myself trying to jump over the pumpkins in the beginning.
(Also, I read the game's name as "Oh naw" in my head which cracked me up for a bit ^^)