I know there are numerous variables and various tricks that can be done to improve battery life but my iphone 5 running ios 7 has definitely taken a performance hit versus when it was running ios 6. Arstechnica discovered a 3 hour difference when browsing wifi connected - specific to the iphone 5 alone: http://arstechnica.com/apple/2013/09/ios-7-thoroughly-reviewed/6/ Middle of the page... This could explain a lot of what I am seeing as I tend to use the browser often. I'm not sure why the problem would only appear on the 5 but I truly hope apple fixes it. Anyway, thought I would pass this along so others don't go mad trying to tweak settings after turning brightness down doesn't improve the situation .