Definitely a tough game
This was a good game to play, though I think that the difficulty ratings for a few of these levels are a bit too low (particularly for levels 6 and 7, because I haven't been able to pass those as of yet). Heck, even 5 was difficult for me before I managed to work out a good pattern for the parts with both the slower small and faster large shots (the rhythm of the music did help there, though). And this doesn't seem to be an issue resulting from not using the slow-down mechanic very wisely, considering that you aren't given much of a window to shoot otherwise. Even considering that the hit-boxes for each bullet is smaller than their sprites (I think), these levels seem a bit harder than 1.5 or 2 stars when you first unlock them (unless the maximum difficulty is 2 stars).
And, yes, I realize that bullet hell games are supposed to be hard. I'm not complaining about that. It's just that the difficulty rankings seem a bit off.
Otherwise, this is a very nice game idea, combining music and bullet hell games, an idea I hope to see more of in the future. I will definitely keep trying to pass levels 6 and 7 (and beyond), and will hopefully continue to enjoy this game years later.
Well Done!