I still use this. I bought it 8 years ago!
I tried other Mp3 players but I always go back to it. Nothing beats being able to just stick in a AAA battery when it needs it, especially when travelling and you can't always find a place to charge your player. Just keep a bunch of AAAs in your bag or buy them from street vendors, etc. wherever you go. Still use it for jogging/working out as well. Also good for having a USB stick for documents too.
It's unfortunate that line is so old and didn't have bigger capacities. They could easily have 32GB models based on flash memory these days for the price it went for in 2003. That said, I find 512MB is actually decent because who honestly needs so much music? I get sick of songs after listening to them a few times and I'm always just listening to new stuff. When I had an 8GB Sansa player (which I bought for a trip to Europe but tossed into a drawer because it was annoying trying to charge it), I barely listened to any of it.