A good start but needs a lot of work and variety.
Its a nice game but the bullet patterns are pretty simple and not generic enough. I'm a hardcore Danmaku player and working on my own Danmaku Flash game. And as I said I am a little disappointed with the patterns. Its the patterns that makes the game and it would be nice if they were actually generated by the music's rhythm. Now it all seems a bit random when they spawn and they are too similar.
Still you have done a good job and the game is unique but it needs work. Also I would not pay for the full game, not with the current frame rate I'm getting and I do have a good computer.
In my Danmaku Flash game I can have over 900 bullets with advanced patterns before I notice any drop in frame rate. You should consider optimizing and perhaps pooling your objects.
Keep it up!