I've entered the MP3 hard drive club, having bought a Rio Karma a couple of days ago. There's lots of stuff I haven't done yet. Haven't used it to transfer non-music files from one computer to another. Haven't ... well, that's about it, really. As I type this, I've stuck 1175 songs on the damn thing ... it rewards obsessive behavior, and it does more as your obsession increases. So, for instance, it's nice to have detailed tags on your MP3 files, because then you can let the Rio DJ do its thing more effectively. I just listened to a ten-song playlist of "country rock" songs ... the only reason I could do that is because I filled in the "genre" tag on all 1175 of those files, so Rio DJ would know what to look for. Here's what it played:

Buffalo Springfield, "Expecting to Fly" (not really country rock, that's my fault, not the Rio DJ's)
Commander Cody & the Lost Planet Airmen, "Lost in the Ozone"
Moby Grape, "Hey Grandma" (I've got to improve my tagging skillz)
Grateful Dead, "Sugar Magnolia"
Delaney & Bonnie, "Never Ending Song of Love"
Buffalo Springfield, "Kind Woman"
Rick Nelson, "Garden Party"
J.J. Cale, "Call Me the Breeze"
Buffalo Springfield, "On the Way Home" (OK, I stuck a lot of their songs on the Karma)
Bob Dylan, "The Ballad of Frankie Lee and Judas Priest"

Among the other "auto" playlists I've listened to, there was "The 90s" (it was almost entirely Sleater-Kinney), "Americana" (it was almost entirely Lucinda Williams), and British Psychedelia (Donovan, the Move, Small Faces, Syd Barrett, Tomorrow, the Zombies). Some of the auto-DJ functions aren't really useful yet ... maybe I'll report back in a month and see how such functions as "your most-played tracks" and "stuff you haven't played for awhile" work.

As for comparisons to the iPod, it's kinda hard when I don't have an iPod to compare the Karma to. I've been playing catchup at the Riovolution site, and it looks like the Karma is much more of a geek toy than the iPod, which has led me to state several times already that, in an interesting shift, the iPod is to the Karma as Windows is to the Mac (and yes, I have those in the right order). The iPod, like Windows, is ubiquitous ... you can always find someone who knows how to fix stuff that goes wrong, lots of software works with it, when people see an MP3 player now they think "oh, an iPod" even if it's another brand. The Karma, like Macs, is different, not ubiquitous, but like Macs in comparison to Windows, the Karma seems to do stuff that iPods don't ... at least, I think that's true, as I say, I don't have an iPod so I can't be sure about that. But my Karma will play FLAC and Ogg Vorbis files, which is v.geeky compared to the iPod, it has a five-band equalizer (and while I don't understand equalizers, I found someone who does understand them at the Riovolution site, and copied his settings), it does cross-fades, blah blah blah. I have no idea which is "better" ... the Karma was better for me because I got 20 gig for $149 ... but it does seem that iPods, like Windows, are mainstream while Karmas, like Macs, try harder because they're #2.