i have one and it is excellent no problems at all bnut the display is tiny i wouldnt put in a single din hole i have mine on the bottom of the a-pillar on the dash its hidden nearly and easy to get to!
buy one!
I have a couple of these in different cars, they are getting better all the time with each software release. The new ones are now great but call quality is also dictated by your mobiles bluietooth connection.
I've got a couple in different cars. My wife and I have different phones, and swapping vehicles was difficult before we got the Parrots, but not now. Installation is much simpler on many cars if you get the adaptor leads. I'd advise getting the Parrot and cable from a company called Siocommunications - this guy is an independent installer based in Scotland, but he does give excellent advice if you have problems, and his prices are quite competitive.