I had a 6S+ for about 8 months and thought it was fine in winter when I wore a jacket, however, as the weather improved the size became more and more inconvenient and it eventually got to the point that the extra size simply wasn't worth the hassle.
I ended up getting an SE and it's the best decision I ever made: I can still do everything on it I could on my 6S+ with the added benefit that it's easy to carry in my jeans, shorts, etc and is far more convenient than the bulky plus sized phones