lives are rather important, but as has been commented multiple times, saving is just the solution. It's not that hard to do and as long as you arent making stupid decisions all the time, you can end the game without losing any lives at all
Arrrgggh...sometimes having good rhythm screws you up...the rhythm is off...sometimes the keys come before they should and sometimes after...its really a pain cuz you have to memorize which ones came before time, etc. so you can get perfect. I'd give it a 3 or 4...