I've got the seat back DVD that came stock in my 07, and I really don't like it from a UI perspective. Clunky if your kids are too young to operate the remote and push buttons on the screen. Which means you are "guessing" from the front seat w/ the remote, as they are not tied into the factory sound system. Turn on the main screen, push a few buttons to get the audio going, push a few more buttons to get the other screen to mirror the first screen (if they both want to watch the same movie), then I don't think it remembers where you ended last when the truck shuts off. I would much rather control everything from the drivers seat, but the reality of the headrest units is you are setting everything up from the back seats.
The only positive is there are two screen down low, in their face.