The BMW nav system is easy to use. I've had it for 1.5 years. Was a bit tricky to setup destinations at the begining but you get use to it.
MP3, Always on TV, DVD and those type of capabilities you will not get - but there are companies that offer extensions to enable this:
www.nav-tv.com and
www.TVonNAV.com
I have not tried it, but you can get the reviews from
www.x5world.com
Hope this answers your q.