At the moment CB2 mimics the behaviors of children roughly around the age of a toddler but where it differs from HRP-4C is that this robot can 'feel', 'see' and 'hear' as well as respond to its environment and the people who are interacting with it - learning as it goes.
It's a little bit creepy to look at just yet but according to this article from Breitbart, Japan child robot mimics infant learning, it, for the most part, can mimic the mother baby relationship (obviously it handles the baby side whilst a human plays the 'mother').
This quote directly from the article sounds more ominous than revolutionary (or is that evolutionary):
A bald, child-like creature dangles its legs from a chair as its shoulders rise and fall with rythmic breathing and its black eyes follow movements across the room.
It's not human -- but it is paying attention.
Sounds like it might just leap up and attack when you're least expecting it.
That aside this video explains just how complex this robot is, demonstrating its Biomimetic Body very clearly. It makes me wonder if combining some of the technology in this robot into something like HRP-4C would bring us even closer to a truly autonomous humanoid robot.