The first one had some sort of problem, and would stop responding to the phone or stop playing music, a reboot often fixed it for a period of time, but inevitably it would stop again.  Amazon replaced the unit quickly and the replacement works perfectly (I am so glad it wasn't my phone!).  I have almost 10,000 songs on my phone now, who needs a separate music player.  It would easily handle video, photos or a monster app collection as well, it's great taking a modest capacity phone and making it bigger than anyone else offers stock, for far less than you can buy the phone with the extra capacity.