Don't get me wrong, this product DOES work. It recharges my iPhone 4S rapidly. The only problem I have is recharging the battery itself in that it takes such a long time and I don't even know if it's working half the time. Maybe I'm doing something wrong, but that's my only gripe.
I bought this a while ago when I was doing a lot of flying back and forth to Hawaii. I used it for both my 1st gen iPad and iPhone 4 since I didn't have easy access to a charging station on the flights. It takes a little while to fully charge this thing, I'd recommend charging it at night like you do your phone but for the amount of power it holds I'm happy with it. It's been able to revive both of my devices on the 13 hour flights. Also has worked for a couple of my friends' phones which are not iPhones but have a micro USB port.