Let me continue to share my misery on battery drainage, but first a clarification because I have seen in some posts that people confuse "Usage", "Standby" and let's call it "total time".
As per apple (http://www.apple.com/batteries/iphone.html) (thanks ag0000):
- Usage: Amount of time iPhone has been awake and in use since the last full charge. The phone is awake when you’re on a call, using email, listening to music, browsing the web, or sending and receiving text messages, or during certain background tasks such as auto-checking email.
- Standby: Amount of time iPhone has been powered on since its last full charge, including the time the phone has been asleep. (emphasis added by me).
So, if you have 2h of "Usage" and 3h of "Standby", it DOES NOT mean that your phone has been powered on for 2+3=5h; it means that you unplugged the phone after a full charge 3h ago, and of those 3h, 2h have been of "Usage" and 1h has been the phone doing nothing.
You may want to double-check your figures because your total usage time, with the correct math, may actually go down.
On a typical day (wasted taking screenshots of the phone):
Usage 21 m -- Battery 94%
Usage 26 m -- Battery 92%
Usage 27 m -- Battery 91%
Usage 28 m -- Battery 90%
Usage 30 m -- Battery 89%
Usage 57 m -- Battery 75%
Usage 1h 2 m -- Battery 70%
Usage 1h 12 m -- Battery 64%
Usage 1h 33 m -- Battery 56%
Usage 2h 10 m -- Battery 40%
30% discharge in 60 m = 90% discharge in 180 m (3h). Put in in perspective - you leave the house at 7:00 am and by 10:00 am the phone is down to 10% of battery life. Hardly something I'd expect from a phone that is meant to be used while out and about, without access to a plug.
Usage is reading NYT app, some text messages, some emails, some google maps, a couple of brief calls; NO viber, no facebook etc.
I am at 6.0.2 and have done all the steps suggested (reboot, recharge, fully discharge and recharge, re-install from iCloud, don't let fully discharge, etc. etc.). I am convinced it is a combination of hardware and iOS issues.