Nice concept, although I would prefer if the light-side form had its own abilities the shadow form doesn't have, and then have the shadow fulfill its own conditions for a transformation. I think in the long run, it could open up opportunities for some interesting gameplay choices - which heart-pieces to collect, when to perform the transformation and the like.
Other than that, there wasn't much content to the game, so I can't quite tell how good potential the intended mechanics had. I did like the audiovisuals; I especially adore the main character's design. ^^