More features isn't necessarily equivalent to "better choice." It's a matter of whether or not you're going to use those features. I'm thrilled - really - that the iRiver people thought enough to put ins, outs, a microphone, and an FM tuner into their device. Really. But the fact of the matter is that if I wanted to listen to the God damned radio, I wouldn't be dropping several hundred dollars on something that can hold every single CD I own, and still have room for someone else's collection. Hell, the reason I want to carry every album I own with me is that I've determined that Clearchannel has turned the FM band into a giant puddle of mediocrity. The iPod is, and not to get into a bit of melodrama, a near perfect, single-purpose device in almost every regard.
Anyway.
The iPod's selling points are firmly rooted in outstanding sound quality (for a compressed audio player, I assure you that even the iRiver isn't perfect), excellent usability (from a company that, since its inception, has been ahead of the curve), and software syncing that's the most flawless that I've ever seen (I dock the thing, iTunes and the iPod do the rest, and I can go take care of other things and not babysit the computer.)
Battery life? Yeah, it sucks, but in the span of 8 hours, I usually encounter an outlet or two so it's not the end of the world that people make it out to be.