I have the Pioneer AVIC-Z140BH and I love this unit the Navigation is great, I have no issues with functionality such as some touch screen units don't respond well when there is direct sunlight. as far as the GPS goes compared to the TOMTOM I had and the Garmin that my wife has I get better directions and better turn by turn than either of those, If you have an Iphone like I do there would be only one complaint that I have, when you switch from Pandora or one of the other compatible apps you have to allow or deny the app to run on your phone but I think that is more an issue with the Iphone OS.
Sound Quality: I have the Monsoon system and I have found that this deck does improve the sound level giving it more of a punch, and I think that I have blown a speaker ( I like it LOUD) but I am not much of an audiophile, I look at more "Does it sound good? yes." "is it loud? yes." then count me in.
there is much more I can say about this deck but I dont want to ramble too much.
it is also really easy with this deck to make it able to play DVD's while not in park/parking break no jumper, resister, or other B.S. needed the tutorial is on youtube.com
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http://www.youtube.com/watch?v=tg3r-HRiYwE) this is the bypass that I did and its quick easy and I have had no issues.
http://www.crutchfield.com/p_130AVIC140/Pioneer-AVIC-Z140BH.html?tp=20212
if you have any specific questions let me know I have had this unit for 6 months and about 8,500 mi