I absolutely LOVED my Sony Mini Disc Walkman back in the day. Had it for about 4 years, took it to high school with me everyday, and had many a band practice session with it hooked up to the amp so we could listen to whichever song we were covering at that time!
But. It bugged me in several ways. 1. The AA batteries that I would go through about 10 of a week! 2. The Software (well, lack of it in any kind of decent way) 3. Carrying the 7+ plus discs around with me into school everyday, which quickly deteriorated.
All those things, is why iPod is now the king of the digital portable music device today. It made it so simple to carry around all your music library without a second thought.
Even though I swore by my trusty MD back in the day, and still have some MD's lying around somewhere, one small machine with my 3000+ tracks on compared to my clunky MD and a few MD's shoved in my pocket, wins everyday
MD's did have a decent sound though, I loved that about them, and the skip protection was a mile better than on my stinky old CD Walkman!