According to the keynote it looks like that peace of crap common UI that I hate with its 720p UI, autoplay and shrinking credits, POS SD startup quality and "we are unable" error popups. I hate this UI with a passion. All the devices use it now even the XBOne which use to have a great interface and now even the WiiU. I think I will be keeping my current ATV3 which starts up right away in HD, easier to navigate, no autoplay or credit shrinking crap and 1080p UI.
Even Netflix website has this POS UI on its page. Much harder now to find stuff and even choose a episode to watch.