I bought a "generic" double DIN unit with bluetooth, GPS and reverse camera off Ebay...thinking it'll be an acceptable unit......had it install properly in my wife's car.
The GPS sucks....takes forever to lock and find satellites, the mapping is crappy.
The bluetooth is patchy, her iPhone and previous Samsung both dropped out all the time....she now uses the iPhone by speaker in a cradle rather than the bluetooth.
The reverse camera is also intermittant....the signal sometimes is upside down or just non existant.....
It does have a good radio, plays CD and DVDs OK........
My advice....pay the extra, buy a name brand, have it properly set up with a warranty thats worth more than the paper it's printed on.