The MZ-S1 excels for several reasons:-Battery life is incredible.-Design and ease of use, especially during long runs, is perfectly suited for the right hand (lefthanded people might find this an awkward fit at first).-The bass is surprisingly full, without compromising much of the treble.

The battery life is good and the sound quality is good as well.

For me, this system works perfectly, and I like the fact that I can put 5 hours worth of music on one disk, the battery life seems like it lasts forever (compared to previous systems), and I can set up the music the way that I want to.

My previous Sony MD player is over 3 years old and still sounds as wonderful as when I first bought it