I bought one of these with the long term plan to install some flavour of linux onto it.
What I found with the OEM interface is that you have full control of the ipod (or CD or storage card) but each time you start up the unit it needs to rebuild the database of tracks. Some times it doesnt connect 1st (2nd or 3rd) time when you start up with the ipod already plugged in.
When you want to check the GPS (or play games) the music stops.
In retro-spect the hardware is good and nicly packaged but iv yet to find a way to change the embedded OS