Early iPods did not have a significant leg up over other MP3 players in terms of usability, other MP3 players at the time hearkened back to the Walkman, which nearly all non-technical consumers were perfectly comfortable with and capable of using.
The big gain there was that the iPod had a modern design, not a design dating back to the 80s.
Edit: The clickwheel was an improvement, but it wasn't like consumers were confused or apprehensive about using the alternatives at the time. We were not like the proverbial grandmothers struggling to check their email in Windows XP; they understood the other products just fine.
The click wheel was good, but it wasn't like consumers were confused by the alternatives. With PCs you could make the case that most consumers struggled to use windows at the time, but hand-held media players haven't had that problem since the 80s.
The problem with the alternatives wasn't that they were "confusing". They were just bad.
I remember trying to find a song on my Rio. It took forever. It was pointless. I came to the conclusion my best bet was to build Playlists, on my computer, and use those.
The iPod's interface made finding songs, artists, albums, etc effortless.
Just because an interface isn't confusing doesn't mean it's any good.
The big gain there was that the iPod had a modern design, not a design dating back to the 80s.
Edit: The clickwheel was an improvement, but it wasn't like consumers were confused or apprehensive about using the alternatives at the time. We were not like the proverbial grandmothers struggling to check their email in Windows XP; they understood the other products just fine.