I got one from ebay that was designed for my Focus MK2 about a year ago. It's okay...
Sound quality is fine.
Subwoofer pre-outs didn't work so needed to use hi-low converters on rear speaker wire
Reverse Camera doesn't come on automatically, no biggy as I don't use it.
Takes about 20 seconds to start, but for the pass 6 months there's a 33% chance it'll start with "System UI has closed" and it takes a good 30 seconds again for it to fix itself... Might try factory resetting it when I get some free time.
The real reason I got it however is that it will tether to my phone, which has unlimited data, and you can install spotify on it. It also has google maps which is my preferred SatNav app seeing it has free traffic. Those are the only reasons I got it.