When I can replace my phone in a watch form factor with 1 full day battery life, that is when I'll get one. There is just no way to power those cell antennas for very long on batteries with 20% of the capacity of a phone battery.
If the watch just became a tool for accessing all the features of my phone, like a dumb terminal, that might actually be useful too. I don't mind carrying my phone, but I wouldn't be upset if I never needed to remove it from my pocket except to web surf on a bigger screen.
But it doesn't seem like these first gen smart watches do any of that. Instead they're glorified fitness bands.