Every time a new iOS update is released, there always seems to be fallout a few days after it takes place. The last major release which was iOS6 caused severe battery drain. The biggest issue with iOS7 seems to be lack of support for 3rd party accessories. There are several other features that iProduct users have found to be less than favorable.
Aside from the normal smartphone battery savings tips like shutting off GPS, WiFi and Bluetooth as well as dimming the display, here are some iPhone specific things: