I have the 1 GB version. It feels a little cheap, and the headphones that come with it are terrible, but it's super light, super easy to use (just drag and drop your files, no drivers necessary), and expandable. When 1 GB SD cards fell below $50 on Newegg, I picked one up, and now I have a 2 GB player.
Also, I like the fact that it takes AAA batteries.
I've been looking at the Sandisk Blue 512mb mp3 player recently...Is it any good?