Very promising. I advocate solar power and hydrogen fuel above all others at this point. I'm well aware that solar power isn't efficient enough yet and we don't have the infrastructure for hydrogen gas, but if we make it that far, we'll have clean and abundant energy alternatives.
Anyway, these bags are sweet, but I'm holding off until they can produce as much energy as your notebook needs to operate normally. That way you can just plug the computer directly into the bag without the battery on a sunny day. I know it's a bit of a stretch...but it will be possible in a few years.