Here, let's see if I can't help. I haven't used the Ipod but I do have an R-900 (Sony recorder) and here would be how I would see it as a direct comparison
Minidisc's (NetMD)
+Size
+Battery life
+Recording (Big perk for me, I must record classes) (You have to hear it to believe it, it's a hell of alot better than any analog tape. No hiss. Crystal clear)
+(MDLP)Pretty good playtime to boot (LP2~160KBPS MP3=2hr20min on an 80min disk.)
+Price (Price in comparison to the iPod though, still expensive as hell)
+Light as hell (Recent recorders with battery and disc are ~130 grams)
+Battery life!!!!
Ipod=10HRS
Recent recorders (Both batteries) 60HRS SP 80HRS LP2 100HRS LP4
Recent players (Both batteries) 100HRS SP 160HRS LP2 200HRS LP4
-Limited capacity in comparison to the iPod (Discs hold only 2 1/2 hours of decent music (LP2) or 80 min of 320KBPS+ music quality music)
-MD carrying friends are rare. Don't expect to be able to swap music, and expect people to ask you "What's that?"
-Non NetMD recorders are limited to 1X recording.
iPod
+Nearly entirely shock proof
+Bottomless pit as far as storage goes
+The machine just looks plain sexy
+MUCH better volume (5MW+5MW for minidiscs, 50mw+50mw for iPod)
+Acts as an outboard storage device
-If you don't listen to that much music, the capacity goes to waste
-Atrocious battery life in comparsion to the Mindisc players. Minidisc players achieved that battery life 4 years ago! The recent Minidisc Players can achieve over 100HRS in the highest quality mode!! (Sony BS's their battery life specs so it's probably more around 70.)
-Size
-Heavy (For me, anyways)
And a new contendor!
The MP3 CD player
+Nearly entirely shock proof
+Bottom less pit as far as storage goes
+CD compatibility!
+Good volume
+Cheap (100$ and below)
+So so battery life in comparsion with the iPod (Can double the iPod's battery life, but won't get anywhere near the MD player)
+Just as easy as the iPod (Good ones support packet writing, .wmf playlists etc...)
--Size (Double minus. These things are pretty big)
-Heavy
The big deal about this type of machine is that it's *really* cheap, it gives you very good capacity, (650MB) and most support CD-RW's. I just can't imagine dragging around more than 2 CDRW's of music (Some people might, the iPod is for them) But I like this class of machine very much.
If you don't listen to *alot* of music, as in just like maybe 20 or 30 songs, a flash based Mp3 player would be entirely enough for you
New contendor
Flash based MP3 player
+Size (Smaller than MD)
+weight (Lighter than MD)
+Cheap
+Good battery life
(+)Recording (not every machine supports)
-Media costs are hell
-Limited capacity
Frankly, the bottomline is that any of the above would suffice for me. I only listen to about 2 hours of music at a time before I switch out music. If you're the same, just get a flash based MP3 player. If you need size, weight, portability, recording, and good batterylife all in one package, you *cannot* beat the MD player. If you need capacity, you *cannot* beat the iPod. The good allrounder for people who are used to lugging CD machines around is the CD Mp3 player.