I have the Dynavin unit in mine. Does it reek of quality? No. Is it functional and feature rich? Yes.
Some of the menu's are a bit of a mess. The CD and USB menu's in particular are rubbish. Whereas the bluetooth A2DP and radio menu's are quite nice. The Nav works well and has guided me to many places without fuss and the A2DP works great and is a brilliant feature that much more expensive products sometimes lack. Using the bluetooth to speak to people on the phone is also easy and clear.
The reason i got my Dynavin was to improve the look of the dash, be able to play MP3 cds, have a bluetooth handsfree kit and A2DP support. If you're looking for high quality, i would recommend looking elsewhere as there are a few niggly problems with it which i should think could be fixed very easily, but Dynavin are hell bent on adding more and more rubbishy features and never perfecting any of them. For instance, the bluetooth phone book only brings up numbers - no names, sometimes the Nav will come up with "OUT OF MEMORY" in Chinese, the bluetooth takes a couple of minutes to connect if you haven't got your bluetooth on before u start the ignition, the CD player is slow to load the next track and you can only skip one track at a time (ie, you can't keep pressing skip track, you have to press skip track, *wait 3 seconds*, skip track *wait 3 seconds*).
Going from something like HDD iDrive to Dynavin would be like going from an iPhone/Android to a Nokia N95. A good feature rich piece of kit, but no where near polished enough to be a serious contender.