Battery is perfect, thats true. But 6h of screen on is like to have it on 20% SB and really not to use it at all. 20 min of calls is nothing. Maybe you guys can get 6h SOT with few mins per day of fb, but screen time out set on 10min? So every time you open fb, you leave screen to turn it off by itself. Screen with showing me, that Android OS is second in battery usage, that means only screen is on, no usage or at minimum and your brightness is at minimum.
I consider myself as heavy user, I get 3.5 - 4h of SOT with 1.5 hours of that is playing COL2 and 30min of playing Farm Heroes Saga (playing in my free time, both of games). Rest of usage is for 1h of call time, around 20-100 sms (depends of a day what business i make) and some small things on web.
1st Android - HTC Desire HD
2nd Android - Sony Xperia Z
3rd Android - LG G3