Graphics, art, and audio are great, and I like the execution of the theme. My main issue though is the gameplay.
Right now the best strategy is literally "stand in the center and mash the shoot button, occasionally turning your characters to face the enemies". That's it. I got to a high score of 452 before I got bored and started writing this review.
The game would absolutely be much better with more enemy types that do different things, like an enemy that switches sides when shot, or one you have to let pass through without shooting it. If you added things like those, it'd be more fun.
Despite the gameplay issues, the game was still pretty good and I had some fun with it.