The other thing is the interaction needs to be fast and practical. Like many IT departments, the internal IT support at my employer likes to follow the latest fad more than being useful, and replaced the dial in menus in the phone helpline with a voice recognition system where you have to describe your problem to be directed to the right area. Of course you don't know what kind of sentence it expects, particularly for a complex problem, and half of the employees are non native english speakers and the damn thing doesn't do foreign accents...