Nice classic platformer over here! I spent a good time on it. I love the transition effect when you fall off the cliff or when the character is bouncing when he die, it's funny!
I think the Level Design can be improve a little bit : There are some jumps, you don't know where you are suppose to land because there are no platform visible at the beginning of the jump. (Assuming you died once and have no information like the coins).
But, overall it's nice! Congratulations :)