I only scanned the first page of comments - but maybe I'm the first one to say it - does this mean I'm pregnant now? :)
I think it's a great concept and I like the simple design. I think improvement suggestions have already been covered by others - it seems it should be the kind of game where you get the satisfaction of having rotated just in time to match that color up to catch the....erm...particle thingies and just got there in time. Then the speed and smoothness of the enemies and rotation influence that feeling quite a bit and at what point you force the player to take a hit from the wrong color (if you want that at all). For a game jam game it's great, and the core is there, I hope you go on to tweak and enhance it later.