Great attempt to make a 2D game look 3D in some areas. It was very compelling and the art in general is very cool.

Once you went to a 3D area, the player character would move up and down very strangely and it would stay like that in the 2D areas too.

For the music, a constant object would have been great instead of starting the music from the beginning for each area. Fading in and out of each piece of music would add an element of consistency between levels.