We got two of these generators for use for demonstrations in science classes. We tried running all sorts of things with them, and found very odd results. We could run certain things very well, but not other things. And then we figured out why: The plug on the device LOOKS like a standard outlet, but it provides electricity that is VERY DIFFERENT than what comes out of the wall. It's DC, not AC. Some devices work very well with DC, others... not so much.
Most people will use this to run phone chargers. For this purpose, it will be just fine, as long as you have a phone (and a charger) that is relatively modern.
So: Great device, but it does have some limitations.