yes your iphone would have to be lying out. As a product developer I feel this is a pretty bad solution.
1) your hand covers the solar panel in use
2) you might have to have your iphone out in the elements while it charged
3) it is not weather-resistant. In places I have lived, it can rain quite suddenly.
There are a lot of portable power options that are MUCH cheaper. Many of them are solar. If you are going on a short camping trip, you can have a battery backup, and just turn your phone off when you aren't using it.
I would have a hard time investing $80 on this "gadget". The money would be better spent on a solar panel/battery storage device that you could use for more than just your phone. For example, a solar AA charger that would help power your GPS, recharge your phone, steripen, and etc etc...
To survive without electronics is, of course, a completely different story. I'm surprised nobody has jumped in here already and bashed it because its an electrotoy