The sound quality is not bad, especially since most electronic devices use the same type of decoding or hardware decoder.
The jetbook has a somewhat higher noise ratio than high quality devices, and a much less flexible user interface and equalizer (it has none).
As far as music goes, I personally love Techno Trance. Especially the music remixed by Kyau and Albert! This kind of music makes use of continuous repetitious beats, rhythms and melodies. And on the surface the music is not bad. But once you really study it, it's composition is fabulous, in such a way that you can always hear something new every time you listen to it.
When I start reading, sometimes I'd add some of their songs on the background, as in "level 1 listening mode" I do not pay special attention to the music, and it's playing very softly in the background. The music then links in my mind to the stories I read!
Ofcourse,if I want to enjoy a song, and listen to it, to learn from it, I will not read, and listen more intently to it!
Although I like the idea of playing back music on the readers, most of the time I take my MP3 player with me, as the reader does not have sufficient battery to last very long.
Usually my jetbook lasts a good 12 hours in reading mode,but between 4 to 6 hours with MP3 playback. happens to be that my MP3 player and jetbook run out of juice around the same time!
So great entertainment doing both! Though I never read more than 4 hours in a row anymore.