Well the I-Pod can be used as a portable harddrive, not just as an mp3 player. I have about 11 gigs of mp3s on my computer right now, and I'm sure I could get a lot more if I had that much space available. On top of that, I can store other files, such as movies or games on it for backup or temporarily, like when going over to a friend's house. Heh, I can keep images of the D2 disks on there so I can play whereever and whenever I want to.
The battery supposedly lasts for 12-13 hours at a time, with a 2 hour charge for the whole thing.
It also has all those little features like that of a cell phone, like a calendar, games, text notes, etc.
Currently, I'm using a Creative RioVolt CD player that can play MP3s (while on a CD). It still works, but it consumes batteries too quickly and is as bulky as a normal CD player, which is too big to wear comfortably.