I have the 6s+, and yeah I can't use it with one hand, but I'm okay with that because I love having the bigger screen so much more. I can see a lot more while typing, watching videos is a better experience, and I've noticed myself using the bigger phone (I used to have a 5s) in new ways a lot more.
Before, I would avoid doing some tasks on my phone like taking more than a few lines of notes. The bigger screen feels less cramped and I don't feel annoyed while using it. In fact I wrote this comment out on my phone. I've never done that with any of the smaller phones I've had.