I like the "one volume control" feature best of all. I used a Nexus 4 and I now own an iPhone, and the volume behavior is... unexpected, to put it nicely. On my iPhone right now, I have the silent switch turned on, so the phone doesn't ring. I'm opening up a YouTube video to see something but I don't want to disturb the people around me. Thinking ahead at the home screen, I hold the volume down button until the volume is at the lowest. I then load up the video, and it starts blaring at full volume. I can't turn it down until it's already making noise? How does that make any sense?

While it might be better to have different controls for everything, at least on Windows Phone I know that if the phone is muted, sound will not play. At all.