Urgh. When will Apple take battery iPhone life seriously!
iOS 8 will show us which apps are draining battery most, but it's basically them passing the buck going 'not our problem, it's that app', when they really should be giving as much battery capacity as they can.
But no, this Apple is obsessed with making their devices stupidly thin and compromising battery.
Some, at least, of the battery problems on iPhones are a result of iOS bugs and not necessarily just the small battery size.
Sometimes when using location apps, for example, my iPhone 5 will get hot and stay hot for several minutes, even after force-quitting the app in question (e.g. Apple Maps or Google Maps) and putting the phone to sleep.
Meanwhile the remaining battery drops 15% or so in a matter of minutes (I have background app refresh turned off globally).