I have been having the worse battery life with my iPhone 5 which I've had since release day. I went into the Apple Store today and they did a diagnose and info showed up on the macbook air stated the batteries was dead and was only at 40%. I use the iPhone a lot but have never had a problem with they past 3 iPhones I've owned The sales person offered to replace the battery for $79. Has anyone had a battery replace before? Do you think its worth it?