The amount of points you get depend too much on your note streak. If you can keep up a good streak without failure, then you are sure to beat every badge, but one little failure can, or, more accurately, WILL mess up your try since it takes very much time to get back up to multiplier 4 again, and by then it is very likely that you have messed up again, and cannot get the points you need. So, basically, if you're gonna miss a note, you'll have to do it in the start or the ending of the song, because missing a note in the middle of the song is pretty much instant failure. Good game though.
Otherwise i would happily rate it a 5, but the positioning of the notes is sometimes outrageously wrong, making the game very frustrating. I, too, have to drop my volume to 0 in order to play the game, because you can't stay in rhythm with the beat since the notes are, like said, rubbish at times.
After you've completed the game, you can just go back to the last scene and complete it differently, so you don't need to complete the whole game again. :)
The teams seem a bit unnecessary, since every AI just tries to shoot MY teammates, no matter what team they are in themselves. Otherwise, a very original and a fun game to play :)
By the way, you don't have to complete the whole game again to get both endings. After you complete it, just click on the last scene and complete it the other way.
The game is very fun :). Though, at the first time i forgot to do the good deed to the potion guy so i had to re-run it, but it didn't take too long :p. 5/5, sequel please.