Bought this before a one month expedition to the jungle in Belize. It works a treat and is surprisingly efficient given how small it is and seems to be water resistant.
The solar panel charges the battery you can see in the picture, this is then what charges your various electronics. The Powermonkey comes with so many adaptors that everything is covered (including everyone else's devices, so keep it to yourself).
Although I was slightly paranoid about it getting damaged by water, it held up well against rain although some condensation appeared on the inside of the panels.
Overall, good buy and would recommend.