Because I'm lazy, here's some basic information about the game from somebody else:
http://kotaku.com/5629125/new-platforme ... 8Kotaku%29
http://kotaku.com/5652475/video-proof-t ... platformer
I personally think the concept behind Ikaruga's gameplay could work wonderfully as a platformer and I will definitely be looking out for this one. While it doesn't appear that enemies will be making much use of the light and dark mechanic, it does appear that many of the obstacles will. I'm expecting the game to change that later in the game and if it has higher difficulties by having enemies enemies that can also switch and have swarms of them attacking you at once. Then there's the possibility that some may end up shooting projectiles at you.