I have been using one of these for about a year now, got it off e-bay and connected it to a freeview decoder box in my glove box. As I spend loads of time sitting around in the car between apts, it give me decent sound quality and the ability to watch daytime films etc. I use a portable dvd player as a monitor for now but plan to install a motorised screen in the dash asap.
Never had any problems with "bleeding" from other channels etc and quality is perfectly acceptable.
I would say that the sound quality would depend more on the speaker quality so my standard Ford setup works fine for me