Pioneer just posted this guide on their website:
http://www.pioneerelectronics.com/PUSA/Apple+Compatibility
Sounds like video-related features are lost, firmware updates on the way to restore some bluetooth functionality.
Well according the AVIC forums (yes, there are forums for a single model series of head units apparently), the apple lightning adapter will for the most part restore all previous iphone functionality to the head unit as far as ipod control and app functionality like pandora. I do believe, as previously stated though, that video functionality may be lost and I don't quite see how a firmware update could resolve this as it seems to be a hardware issue. There is a cable version of the adapter that is slightly more expensive, but it will probably look and fit a lot prettier than a brick-like adapter.
Personally, I've never played a video on my head unit from my iphone in the first place and I can't quite fathom the point since the screen isn't all that much bigger, but I can understand how this may upset some. I don't see this as stopping me from upgrading to the 5 though.
