You must use your iPhone a lot more than I do. I usually have 25% or more battery after 16 hours. That usually includes an hour or so of streaming audio over cellular, and snapping half a dozen pics. Of course I would expect my battery to drop a bit if I played more audio or video on a typical day, or if I played more games. I usually play games on the iPad. In fact I use an iPad at work and at home quite a bit, so that probably saves a lot of my iPhone battery now that I think about it.