If you need a small panel that is inexpensive, will charge your phone/tablet AND has an internal battery, this is a good deal. It performed nearly as well as is its sibling and Editors' Choice winner the Instapark Mercury 10 and yet was half the price. The Mercury 10 produces over twice the power and can charge two devices at once. The Mercury 10 is better if you don't mind a little extra weight.
After about 3 months, the 4S panel stopped working that well. It would not hold much of a charge and when plugged in, it stopped charging the iPhone short of a full charge… even in direct sun. Other user reviews have reported similar problems. For this reason, we need to test a few more of these devices before we can recommend it. In the meantime, if you are looking for a good budget and compact solar charger, we recommend going with the Anker 14W. But the 4S has the advantage of an internal battery and it can be easily clipped to your backpack while hiking. For the Mercury 10, we generally recommend getting an extra external battery, which further raises the weight and cost.
Got a laptop or larger device to charge? Read our full Portable Solar Review to see the more powerful options.