Oh yeah, that is really great feature from Bethesda, I like expressions in ES Oblivion too, my character is so gloomy to ones she hates, and beggars.
Yea, Jericho frowns like crazy when he sees someone he hates, but his smile...*drools*
Anyway, all of my characters get a "I'm going to eat your soul" kinda frown when fighting.