1) Use of iTunes, a bloated and unnecessary program, is required.
2) You can't transfer things back onto a computer after you've transferred them to your iPod. You can delete the tracks from your iPod, yes, but you can't transfer them to your computer.
Both of these issues can be gotten around using various iTunes surrogate programs, but they're also issues that can be avoided if you go with another product, and you'd also probably be saving yourself $50 in the process. I've had a 40GB Creative Nomad for two years now and it's done me no wrong. A friend of mine has a Zen Micro and has been using it fine. As DAYV points out, results may vary with Creative's products, and that's a valid point to consider. Just shop around, but those the two reasons I stated right there were the deciding factors on my not getting an iPod.