This game is fast paced eye candy for the arcade shooter fan in all of us.
Galaxies is simple - destroy everything that moves and acquire score multipliers after you've destroyed the moving things to enhance your score. In this version of the game you have a companion polygon that assists you in destroying rival polygons. It can attack, defend, gather score multipliers, etc.
So far I only have positive things to say about the game. The particle effects are awesome, as is the space-time grid distortion. This is definitely one of the better games on the Wii.