Hi,
SWMBO loves them, has an MP3 player and often listens to stories when we are driving. In her own car, the cd player will take MP3 disks and plays them in track order.
I rip the tracks for her, and put them on the ipod thingy with itunes (I hate the interface and have to relearn it each time I use the damn thing).
I can't drive with music or audio playing anymore - guess the number of brain cells is diminishing with age, and won't process all the information simultaneously.
cheers