Pre iDrive sat-nav in this isn't worth having imho and as Fox says sticks out like the proverbial sore thumb.
How does it stick out like a sore thumb? It's a flip up/down screen not a big hump like in an e60 or not in an ideal place like an e46/e39.

I'd beg to differ with the 'not worth having' as well, Its good not only for navigation but ipod control (with Intravee), MP3 CD changer control, TV/DVD etc. etc. Maybe its one of those things that if you've had then you can't really do without. I had nav on my e46 before my Z4 and nav was a definite must have for me, especially with the Intravee.