Here's my experience with the battery thus far:
Friday:
Bought it on launch day and had 90+% and tested/play with it till left with about 50% when I got home. Did what the Singtel person said to charge it 8 Hours plus on the first use.
Saturday:
Woke up happily brought out my iphone, left house at 11am with 100% battery. Went to nice places test the camera, keep snapping away. Drained to 65% by the time it was 2-3pm. Starting to get worried switch off 3G data when not in use etc and only use it when neccesary. TO MY DISMAY it keep decreasing by 1-2% every few minutes. Dropped steadily even with so many things switch off

even worse than my gf's iPhone 4S!!! By the time it was 6pm it was dead.
Very disappointed, went back home and charged it. Kept hoping to myself it will get better.
Once it reached 100% battery life, left my iPhone alone with 3G data off for the rest of the night while i went to sleep, see whether got battery leak anot.
Sunday:
Woke up, look at my iPhone AND THANK GOD still at 100%, surf the internet awhile with 4G on for 1hour + dropped to 92% (Finally it is behaving like the iPhone 4 battery life and I felt relieved).
Charged it back to 100% and left the house for the day. For the entire day I left 4G on, Location service on (for instagram and twitter) and guess what! At the end of the day reach home around 8.30pm only drop to 71%


Chose not to charge my phone for the rest of the night as I want to see how it goes.
Monday:
Woke up and saw that the battery dropped to 69% (still very good) Went to work and till about after lunch time I decided to charge it. (was about 35%)
I am VERY impressed with the iPhone 5 battery life thus far!
Let it fully drained once, and charge it one time good one for about 8 hours.
Note: (I will off the data when I go to bed, and switch the Do not disturb mode on)
Sorry for the long post. Hope it could my experience could be of assistance!