I can see a lot of use in "I don't really want to record video and worry about how I look today, but this stupid poop can share my exact facial expression".

I don't have an iPhone and don't plan to have an iPhone, but this is going to be a surefire hit feature for Apple, and I expect other platforms to try to emulate it pretty quick.

Also, a friend of mine pointed out how popular it will be among the furry community. :)