It's a personal phone not a work one, so I took the risk and upgraded my 6S yesterday. Works a treat. Not sure why, but even Facebook works for me without crashing. In fact, apart from maps.me every app I have works, including the Microsoft Word Flow keyboard, which I was sure was going to be a casualty. Heck, even Safari is holding up. Performance is good as is battery life.
I'm getting some issues with notifications not clearing properly (but I'm finding the whole 3D touch, click, swipe, dismiss options confusing, so there'a learning curve for me there) and my IMAP mails aren't fetching to the set 15 minute schedule (and before I'm sure they were using IDLE as I was getting pretty near instant notifications of new mails) but nothing that's causing me big issues. iMessage, FaceTime and the phone are all working and ringing and connecting as expected.
My main problem though is that after only 24 hours, I start to use my iPad mini (no iOS10 support - boo) and it looks so old fashioned already, especially when pulling down the today widgets.