As a developer/geek, I'll probably get half a day out of my oft-fiddled-with watch. But I'll just carry my phone charger battery and use it to charge up the watch. The watch charger cable seems to be a regular USB cable on the far end, I can plug it into the charger battery, my laptop or whatever, and it probably will take less than an hour to charge it - perhaps substantially less.
Carrying around a charger for a WATCH, what great future