Like anyone with an iPhone, battery life's an issue. The answer seemed to be this external battery. Well it's not. It can get you out of tight spot if you've recently charged it but it won't keep you out of that spot for long. It certainly won't double the battery life of your phone. It's an inelegant design as well, feels cheaply made and has rediculuosly bright LCD lights draining it's precious power. It adds a lever effect to the USB port which I can see ending in misery - there's no way I'd stick it into my pocket while connected to the phone. It's expensive. Having said all that, there aren't many alternatives and iphone users are used to compromise on the juice front.