This was a lot of fun. I really like the bumps that throw youin the air and the geometry change of the player. Graphics look nice and the gameplay is fun.
Some minor things i would critique: The levels seem to be almost the same at some point. Maybe introduce a new mechanic later in the game or fewer levels; And sometimes you loose all lives at once when hitting the obstacles, wich seems unfiar, some invisibility frames after loosing a life would help.
But all together nice entry.