So, if you use your mp3 player for 8 hours a day (some do) you replace your battery twice a week... at $1.25 a pop. That's $130 a year. OK.
I think $20 every couple of years to exchange the rechargeable in the iPod is better... and more economical.
With an iPod, which has the capacity to hold thousands of songs, replacing songs in less than five minutes is unnecessary... just keep them all on the iPod.
I sense an Apple iPod zealot. I was using worst case of $1.25 for a single AAA purchased at retail. In fact one can buy 12-packs for substantially less that $1.00 per AAA, or a top of the line charger with 4 or 8 included rechargable 2000ma AAAs for less than $50.00 (good for 300 to 400 charges).
In any case my point was simply that the iPod Nano is not the only MP3 player out there, nor is there anything new or advanced about it.
If you want to argue that case, have at it.
And, no, I don't use my MP3 player 8 hours a day, 7 days a week.