I don't know if it's just me but I would have liked a separate button to turn off music and sound. Sometimes I didn't want to hear the background song but still wanted to hear the sounds.
Origanlly I was going to rate it 3 but the second they said "the cake is a lie" I knocked it down a point for a FREAKING PORTAL REFRENCE! Seriously, why must everyone insist on using a line that even Valve didn't use in the second game.