Facial expressions and emotions are one of the toughest thing to achieve for CG and Android Robots.
Have a look at the latest development in Androids trying to mimic human expression. Scientists have created a robotic face that can accurately mimic six human facial expressions. I feel it is still far away compared to CG. But it is a good attempt to cross uncanny valley. I know how hard it is to mimic humans emotions and apply that into quantifiable limits in robots and 3D.
Real time digital human facial expression
Making of digital Ira