I tried Napster on Tuesday after getting an e-mail saying it was up and I could get 5 free tracks. Nothing worked -- not a terrific first experience. I'm back there this morning, and my free tracks are downloading nicely. The interface is still kinda quirky, but at least it works. And the download progress window is a kick, with a hint of nostalgia because it looks a little like Napster did back in the day when more than 5 downloads were free.
One neat feature is the ability to look at Billboard charts dating back for decades, and then buy music from the charts. Those charts could be dangerous (=expensive) for me. In just a bit of peeking around the edges, I noticed music that's available on Napster but not on iTunes. For example, Napster has five Pretenders albums, iTunes only one.
I don't like that Napster's music is locked up as WMA files that don't work on a Mac or iPod, so I won't be buying too much. I wonder if you can do the burn-and-rip trick to turn them into MP3s.