I've seen a lot of complaining about the S5 lately - mostly the lack of root. I came from the S3 and am also patiently(?!) waiting for root. I wanted to share my battery life. So far pretty amazing. Granted, I am not a heavy user, but do monitor emails, texting, a bit of internet searching and photos. I think the most I ever got out of my S3 was 30 hours with very minimal usage. Average usage (about the same as this test) was about 18 hours.
I have the location mode set to 'Power saving'. Also, display brightness is on Automatic. Power saving mode set to On. Other than that, I don't think I changed any settings. I am on WIFI most of the time as well - home and work totaling almost 21 hours a day.
It'll be interesting to see once root is here and custom Roms available, how far this phone can be pushed!