I'd like to see a sandbox mode. It'd be fun to experiment with otherwise impossible stats. Maybe make it an unlockable for people who have earned every achievement (such as myself).
Once you unlock every achievement the game begins to get sluggish and painstakingly slow, as you begin to progress passed 270 multiple times a day.
Danmaku is always fun as Hell. It's always a challenge and you made it your own. Bravo Kupo. There's a bug here or there, such as things not responding where they should (people mentioned the press any key one). Other than that, great game.