I love the standby on this thing. Not rooted or using greenify or anything. Leave it at home for 10+ hours when I'm at work on standby with wifi on and the drain is only 3-4% by the time I get back. I only charge this thing every 2-3 days at <30% with a few hours of moderate use every night at home.
Then again it's still fairly new, but its like night and day when compared to my GS3 which drains like a mofo on standby.