Here is a video of the polarity in action. The same color bullets bounce, different colored bullets damge shields. Some enemies adapt their polarity to match the polarity of the bullet that just hit them, some cycle their polarity, some have static polarity. The lower angle has been changed back to a 45 degree angle because of lack of critical comments.

http://s293.photobucket.com/albums/mm42/mith_photos/?action=view&current=polarity_pre.flv

You will also notice that the bullets move more smoothly, they accelerate once fired instead of having a constant speed. The crosshairs now extend to the edge of the move area, allowing you to better target incoming enemies. The damage that the bullets do seems random but instead is based on a minimum/maximum damage (plus a bonus) damage calculation; the same goes for explosions. The shields look cool as well.