i have the 5120, its sweet. finally got the bluetooth put it a couple of days ago, its awesome. it automatically uploads your phonebook in and you can setup voice prompts to dial each person just by talking. plus i have the ipod cable in the glovebox, so you can control everything right from the screen, no messy wires. make sure you get it bypassed too!! awesome unit, i love it!
i have heard the 8120 is the unit to get though, some people have it on this board and really recommend it. either way though you cant go wrong with a kenwood, very intuitive right out of the box and they have all the features you would ever want.