The volume function works for computer, iphone 4 & 5. It doesnt change volume of phone, just the output volume. Thats why it works with any.
The single button should come with an instruction for people that doesnt know how it works. But "1 click = answer, hang up, pause, play", "2 clicks = next track, fast forward", "3 clicks = 1 track backwards, rewind?"
Sound: Its better then expected! Playing Calvin Harris at work as im writing this and the base is pretty awesome. About same quality as Jays 3-4, but 10% of the price.