Best battery on any smartphone I've had so far, great, great numbers constantly, you need to make some adjustments and disable unused apps and features but the results are great.
Here are my stats from yesterday, mobile data on all the time during the whole day, only off when used Ultra power saving mode during sleep time, about an hour on YouTube, browsing and using emails all day plus a little over 30 minutes on Bluetooth paired with my Gear 2 Neo using it with S Health while running, Streaming videos from Youtube and Vevo and 1 movie from Crackle through my Chromecast, so far very impressed. Notice that when I say that some adjustments are needed I mean, notice how my Screen is again greater than Android system, and that's something that since the kit Kat update on my S4 I haven't seen.
Just have Location reporting off, OK Google voice command off, turned off all Samsung apps except Samsung Apps, S Health, Gear Manager and Calendars, Location is off until I Need it, I have all the air gestures and motions on except Stay on, well to many things to explain but in a summary I have everything I possible can think of using turned on and using them and I still manage to get this great results.