I used the Dexim while hunting for hogs. I was able to tweak my Apple iPhone 4 so that it used minimal power while out on the hunt with Gaia GPS. This made a huge difference. With these power tweaks, even with several hours of GPS use I still had around 50% - 60% battery when going to bed. Normally, my battery is gone by the end of the day.
Then I used my Dexim solar charger to top off my phone at night. The Dexim is a good portable battery for short trips. Its strength is its size, and when out in remote areas, size is very important when backpacking or hunting. The tradeoff with size is that, the solar cells are pretty small, and as a result, it takes way too long to charge up all the way. However, if the Dexim is topped off before embarking on a trip it could be used to charge your iPhone nightly on a 3 - 4 day trip. If the Dexim was left at basecamp, and the solar cells got good sun all day you might be able to stretch that out even longer.
You might be asking yourself, are there better solar chargers with bigger solar cells? Yes. However, for the price and size, the Dexim is a good value.