I have an iP7 with 10.0.2 and getting horrible battery life since day 1. I restored from backup on release day so there's no way that there is any additional restoring being done almost 2 weeks afterwards.
With previous iPhones, last one being the 6S, I typically went to bed with 30%+ left. Now I'm seeing down to 35% or so at the end of my work day. And, as a matter of fact, this is with less than typical usage compared to when I had my 6S due to me noticing the battery doesn't last as long for me.
I've upgraded to the newest iPhone on release day for the past 5-6 years and have ignored the battery threads that get created since I always had great battery life but I'm definitely having a bad experience this year. I thought this phone was supposed to be good with battery due to the lower power cores in the A10.
Hopefully this can get remedied soon with some software updates. As some have mentioned, this might be due to the poor signal I'm getting with the 7 on Verizon, whereas I was getting great signal with the 6S and before.