I told my wife (who does not own an Apple Watch) that she should get one so we can use this feature. She is always trying to say something to me when I'm in the next room and can't hear her. She called me a watch nerd, and reasserted her lack of interest in the Apple Watch. 😛
We kind of have this thing where I keep telling her the Apple Watch will solve her problems.... when she can't find her iPhone, when she misses a call or a notification, when she wants to control our smart lights or music but doesn't have her iPhone next to her, etc. Nothing will convince her.
I do think it could get to be an annoying feature... like those people who have loud conversations in public while using the speaker-mode on their mobile phones. It will be interesting to see how much it gets used. It's kind of in between dictating a text message and just making a phone call on the watch.