Hi kramerica,
I bought an appradio in the USA recently and had it installed in my car here in The Netherlands. I have been told the wiring is a bit different, but couldn't give you specific details on that since I'm a noob when it comes to the technical stuff. However, it didn't pose a significant problem and installation has worked fine until now. I am very happy with it.
Radio frequencies, because of the difference, DON'T work well, but this still needs some looking into and trying things out. I am hoping that with installing the European soft- and/or firmware the frequency problem c