I've been waiting for something like this. I got some ideas for settings.
-if you could set it up to stay on whenever it is being charged.
-option to display videos on the iPad or output to headrest monitors etc.
-when power is not sensed, so if you turn your car off the music is paused and it automatically locks the screen.
-set dim times, so you can specify that it dims from 8pm to 7am because it gets very bright at night.
-tethering option within the app to connect to MyWi etc for wifi only models.
-music search integration. You might checkout SoundHound. It let's you find songs with voice control and displays lyrics and YouTube videos so you can listen to full song.
-customizable themes, or at least some features to change it up a bit.
And integration of music and video library....