Despite Android version of S4II, sometimes, the button does not work, such as stopping music playing or skipping a song. It would not respond at all or take an eternity to respond. Often times, i would just unplug the earphones from my Note 2 and then plug it back in...and voila, it works again. An annoyance.
BTW, i am using my S4II with Samsung Music Player. For whatever reason, my playlist/songs (from iTunes) would get randomly deleted when using Google Music app. Samsung Music Player has not done that. Weird.