I have used many of those little solar chargers and couldn't get a charge on a small cell phone in direct sunlight in any reasonable amount of time. They just don't have the surface area to capture enough energy.

I used to have the UltraLast Green Solar 2 AA/USB, which is virtually identical to the one you mentioned.

I wouldn't get either one again. If I was last-minute, stocking up at a store after the SHTF and that was the only thing there ... I might grab a couple. But, it is my last choice in solar power. Right now, hand crank devices and Powerfilm are the only true well-functioning products.