Funny enough, that's what kept me from upgrading S4 -> S5 - all the stories of people saying the battery was worse than the S4. Anyways - I decided I just really wanted a Ceramic S4, so I bought the S5, turned off the display and getting ~60 hours out of a full charge, which is better than my S4 by ~10 hours. Disappointed I listened to all the negativity but should have known most posts here are for people with issues. I posted a photo here somewhere the other day of my usage and the battery time etc. Colour me impressed.
(I use my watch as a communication device, not an activity tracker - so I never use GPS etc)
Funny enough yesterday, I figured I might as well try the AOD, and I'm getting 24 hours usage on 50% battery. So, less than I was with AOD off, but still, as much as I was getting on my S4 - so I can see why Apple rated the battery at the same operating time between the two models.
The S6 will be even better, I'm sure - and seeing how much they were able to actually do now with the battery/screen on the S5 I'm even more intrigued at what's next!