I have an iPhone 4S and this cable is useless. As others have pointed out it is the length that Apple's cable SHOULD be -- but unfortunately doesn't stay connected to the phone enough to charge. It doesn't fall off, it just looks connected but isn't really (and therefore not charging). It can start out connected, but then the slightest jiggle of the phone will cause it to stop charging. So you can't really use your phone while it's charging.
Don't waste your money unless you KNOW it works with your device. I've only tried it with an iPhone 4S.