I'm impressed! I had not been using the MP3 function of my Zumo 665. I loaded up a 4 gig micro SD card with about 12 albums. It has a really nice interface and handles the MP3's well. It works much better than trying to use a CD input type MP3 player. It's easier to read than an IPOD and it's rain proof so you don't have to worry about it getting wet. You can setup playlists as well. And it has the advantage of being able to hear the GPS, XM, Phone, etc all on the same interface. I was impressed with it before. Much more so now. I suppose the only downside would be the limitation of a 4 gig micro SD card. You could certainly carry additional cards. But I'm good with the limitation. It certainly presents a good alternative to the MP3 players.