For me, 8 hour battery life is more than enough. The biggest plus is the drag and drop capability. I hate going through iTunes or SonicStage or any other bundled software.
My first mp3 player was an iRiver which I used alot till the buttons started to fail after a couple of years. Then I borrowed a Sony from my friend for almost a year before buying a Nano which is I use now. Wanted to switch back to iRiver for a while but nothing seemed particularly impressive until this.
When it was first announced, they pegged it against the new Shuffle but now it looks like they'll put it up against the Nano so I'm guessing the price will be higher than I hoped =/