Well after a few days of usage, I can confidently say that my battery life is quite a bit worse. I used to go to bed with around 30-40% left, now it's pretty consistently below 20%.
This is a weird problem for some it seems.
When I updated last weekend, the first 2-3 days my battery was worse, draining a lot quicker.
One thing I noticed was the messages app was using almost 60% background usage!!
That could not of been helping. Read a few posts that said the messages app was doing some sort of cataloging with other apps such as the photos app.
Weather that was true or not, Im not sure, but iMessage usage has cleared from my battery usage page altogether now.
And since then my battery has been just as great as it was before ios10.
Im on a iPhone SE.
When I first updated I made sure I done a few full charges and powered off/on the iPhone.
Ive also turned off a few things I don't use including:
Siri OFF
Raise to unlock (new feature in iOS 10) OFF
Reply to message (new feature on lock screen) OFF
Bluetooth (only ON when I need it)