I have owned this deck for 2 years now. It is an amazing deck. I got just the deck no gps nav system because navigation changes over time. At the time gps nav was new so maybe it's better now. I kinda wish I bought the nav package though :-(
I am running it through alpine amps running all infinity(5.1) speakers and 12' subwoffer. It sounds really good and no problems with sound system at all.
CD/DVD-DL music and movies playback, SD card 2gb max, PS3 video game console hookups , bluetooth works awesome(i use to stream music through pandora from cell phone and phone calls), you can hook up external usb HD, the external adapter has the game console hookups and usb connector, to play music( i have 250gb hd connected in the dashboard), easy surround sound control, the touch screen is very responsive and easy to use.
Every now and then the clock time is off by 10 minutes. The worst I saw was 6 hours. The 6 hour thing has gone away and have not seen it since
The usb connection is v1.1 not 2.0 so it takes a bit to load a large amount of music . In my case the 250 gb take about 1-2 min to load but once it does switching/listening to songs is very quick.