I just installed this unit in my Smart and although I'm not completely happy with the unit yet, I love how easy it was to install and it looks factory. It's been a long time since I installed an aftermarket radio in a newer car, but I had the stock one out and the new one in in just 30 minutes. I bought it mostly to play music and DVDs and so Navigation would just be a bonus, but after trying to read the instruction manual which in itself is nearly imposible to understand, it still took an hour to figure out how to get the dvd past the disc menu. I even called Crutchfield, and they couldn't figure out why it wouldn't work either. I finally figured it out, but it wasn't at all like the manual explained. The user-interface is also a cluttered mess. I heard that playing dvds is easier if you buy the optional remote control, so I will be getting one. I haven't even tested the navigation yet, but at least it's a Garmin.
Oh, and if you want to watch dvds while your driving, just hook up the lightgreen wire to ground rather than to the emergency brake wire, piece-of-cake.
I'm sure I will get use to everything, but I do wish things were more straight forward. It does sound 10 times better than the stock cd-changer. Does anyone else have this unit? and what are your thoughts?