niche product. microsoft is pushing more the technological envelope than the social envelope. compare microsoft and apple ads: it's significantly easier for people to buy into ipod because they keep their marketing so much simpler. microsoft is throwing too many acronyms around for people to care.
wifi is a nice idea for portable media, but it's going to take a better marketing team to make it happen. before the ipod video, no one needed to be able to watch videos on their pmp/pmc. there certainly were already ways to do this (either hacking older ipods or buying other pmps), but the way apple added music videos and tv shows to itunes, it became successful.
zune gives people the ability to share. but microsoft isn't doing anything about what they're going to share. so in my opinion, it's going to be largely under-utilized, unless microsoft learns to take advantage of how apple's been marketing the ipod for years.