Perhaps the spec you really should be comparing is volume, not thickness. Volume is miniaturization (progress). Thickness is a design choice. Incorrect specs isn't really forgivable though.

I hate to give the kneee jerk karma-is-great answer, but I honestly didn't feel like the iPod's interface was that intuitive when I first tried one out. (Though mainly I just kept searching for the insert/append/enque menu, which didn't exist)

Matthew