How is he 'confusing people' when he says 'As far as I know' meaning there is an open possibility he could be wrong. Please - actually read and digest what people write rather than quickly scanning then coming to conclusions.
Anyways, I can say after a week I'm growing tired of the white/brightness. Especially at nighttime. Apple doesn't have to incorporate themes. But I'll gladly take a section option for a darker refined theme.
My battery life was still so bad, even after I turned off auto app update and most location services, that I downgraded back to 6.1.4. I will stick with it until the Beta 2 is released and try it again
There is a number of studies which show that black screens do in fact drain more power. It's not huge, but again, my post wasn't entirely serious to begin with.
Also, a white screen (or at least a bright image) requires less backlight, because it is quite bright itself, while a black screen (or say, a dark photo displayed) requires more backlight to bump the contrasts. Such adaptive backlight is often used in many devices ranging from TVs to laptops. I don't think iPhones do that at the moment, they only respond to ambient light, but they may begin from iOS 7
Although I'd rather they didn't.