One interesting point in review is that she is finding the function for sending heartbeat of small sketches useful. I think these were dismissed as more or less useless demo stuff right after the launch by some journalists.

Now when I think more, the sketches could be actually quite nice quick and discreet way of communicating with close friends. Quite quickly you would probably come up with simple symbols for various things.

Here could be a network effect that would help Apple sell more watches. Get an Apple Watch or you are excluded from the communications.