Bought over a year ago, and it charges up my iPhone approx 2 1/2 times before having to recharge. Recharging is easy with the built in plug. Glad I have this for the times I don't have access to an outlet.
I've had mine for over a year now. I do a lot of traveling and it is great while on the road or then you don't have a power outlet nearby. I can get roughly 4 complete charges out of it on my Iphone 4s. It's light and the fact I need any additional cables for my phone or any other micro usb device makes it awesome. I have had no issues with it at all. I'm looking to get another one since getting a new phone. Now I need one with the lightening connector. Otherwise I would keep using this one. Very light in the backpack and plenty of charge.