PLEASE don't put a sudden scare like that ghost thing appearing out of nowhere over and over again! I beg you...I almost decided not to finish the game because of it... Aside from that, though, great game!
I also feel that getting the hard badge feels like it is a matter of luck, but I do not believe that that makes the game itself bad. While it is true that the hard badge is harder than most, I doubt that the game developer was anticipating a 100,000 point badge when he/she was designing the combo system. I agree that a mute button would be nice, however.