I had the BMW version installed in my 2007 Z4 and it works great. It works through the nav system display and uses either the radio controls or the steering wheel controls. It mounts in the glovebox and will charge the Ipod while plugged in.
It has only 5 "playlists" available but each one will hold 255 songs.
It didn't come with directions but I was able to find them on the Apple website regarding Ipod interface with BMW cars.
If you don't preface the playlist with BMW-1, BMW-2, etc, it won't recognize the playlist and will divide up your main music gallery into 5 sections of 255 songs each (until all songs are included).
BTW I am using an Ipod Classic 120 Gig.
Hope this helps.