I want to thank Martin for his review which avoided me having to figure out the play method of the unit on USB drives. The unit works well, has good volume and sound (at least by my ear). Since the tuning and voulume knobs are in the rear, you have to feel for them, but they work well and it isn't picky about geting a good signal. I was a little surprised at how small the unit is.
The USB port works well, but the display only tells you which track and how long you are into that track. At $30, I didn't have a right to expect too much, but was pleasantly surprised.
Edit as of May 2009:
This unit is in my wood shop so I admit the problem I'm now having may be related. The volume is not working properly. You choose a volume and later I can hear it go up slightly, then you can't turn it down regardless of moving the volume knob all the way down. I don't sand much (prefering other methods) so that isn't it and I've tried blowing out the knob with slight air pressure - that too was to no avil.
After a few hours, it will go silent meaning the volume knob is working again. Don't know if this is a problem with this player, or if it's just mine, but felt I should mention it.