What features are lost on the Lightning to 30 pin dock adapter?
The iPod out functionality is actually a very specific feature that was added only very recently. Only a few cars actually support it, so the vast vast majority of appliances should continue to work fine.


  Here's the thing, though: "iPod Out" doesn't actually mean "audio output from an iPod." It's the branding for a very specific feature for cars and remote-screen tools that was included in iOS 4, which delivered a customized iOS graphic display via the in-dash screens when the device was docked


http://www.tuaw.com/2012/09/13/lightning-30-pin-adapter-works-with-analog-audio-ipod-out-doe/

For the Video functionality, this will be coming soon - the connector is capable of it, but it most likely requires additional circuitry in the adapter to implement it.


  As with the 30-pin connector, the Lightning connector supports video output; Apple told Macworld that Lightning-to-HDMI and Lightning-to-VGA cables will be available “in the coming months.”


http://www.macworld.com/article/1168555/what_apples_new_lightning_connector_means_for_you.html