My impression is that the device isn't able to track all of the face's subtle movements so the avatars come across as seeming relatively expressionless. For ex

My impression is that the device isn't able to track all of the face's subtle movements so the avatars come across as seeming relatively expressionless. For example, I noticed that Lex's and Mark's eyebrows don't seem to move as much as you might expect given the emotions communicated by their voices. I assume this is either because the device literally restricts the movements of the eyebrows (perhaps they're pressed down under the headband) or it just isn't able to track them that well.