You haven't had your phone a year yet, wait till then to boast your battery life. Of all the iPhones I've owned, battery life is good for the first year, but after that it sucks big time, major drop off in performance. I realize batteries don't last forever and they slowly lose their charging capacity over time, but after the first year they get to the point of useless and Samgsung's commercials protraying us as wall huggers for power is 100% the truth. I use my phone the same as everyone else on a daily basis. Love it till the battery life fades.
The new hardware and software in the 6s would really, REALLY have to be optimized just to keep the same battery usages figures as the 6, much less it having better performance if this article is true that it will be a smaller capacity battery. And don't count on that battery saver mode to do anything, it's almost the same as putting it in airplane mode. I recently had beta iOS 9 on my phone and it didn't do jack, I didn't see any difference, but maybe because my battery is already shot as I have a 5 model.
The masses are already complaining about poor battery life, Apple coming out with a new phone that doesn't increase performance isn't going to be well recepted.
It should be common since that when you make a device that has expendable parts that can't easily be removed and replaced by the user, that part of the device should always be made better, not made smaller and an expensive hassle to get replaced by Apple.