Rhythmbox looks very promising, but I ended up running into too many problems with it. Visually, it is an iTunes clone. The biggest problem was that it would not play 192 bps constant bit rate MP3s that I had ripped with Music Match Jukebox on Windows. At some point, I will update the version I have installed of the GStreamer media framework that Rhythmbox relies on and give it another try. Either that or try to use Rhythmbox with Xine for the backend.
Another big problem was that it used 5-10% of the CPU while playing music. Zinf uses less than 1% of the CPU. That makes a big difference when you are trying to do a lot of other work while listening to music.
Finally, Rhythmbox was really, really slow to start. My music library is currently about 40 GB. By the time I finish ripping all my CDs, it will probably be about 70 GB. If I rip all my LPs, too, I could easily end up with a library over 100 GB.
Zinf does the simple things very well, but it also has room for improvement. Better Unicode support for MP3 tags would be really nice. Although it doesn’t have as many audio drop-outs as Rhythmbox does when I’m doing other CPU intensive stuff, it does happen every now and then.