It can be pretty useful, actually. I was cooking dinner the other night and needed to set a timer. My hands were caked in all sorts of gunk from the food I was making. I turned to my phone and said "OK, Google - set a timer for 10 minutes", and it did it. And last night I was watching a movie with my fiancée, and we thought the actor in it might have played some other character in a TV show we watch, so I simply asked my phone. It took a couple of seconds, and gave us the precise answer.
It's got nothing to do with a "cool factor" - instead of converting your intention to a series of physical gestures on your device (finding the right application, typing in a search query, looking through the results for the answer), you simply voice your intention, and the device does the rest. That seems an efficient use of a device, not something "cool".
And you don't have to shout - to claim that smacks of trying to make the whole interaction seem absurd, comical, or impractical - which doesn't exactly reflect well on you
We are not a loved organization, but we are a respected one. -- John Fisher