I will be the dissenting opinion. I used my 6+ for two weeks. I desperately wanted to want to love the 6+. Between the larger screen, better battery life, and optical image stabilization, what is not to love?
When I first opened it, it felt huge in my hand (for reference, my hands are 9" from outstretched thumb to pinky). It was just too large for me to use one-handed comfortably. The last straw was a trip to the grocery store after my wife had texted me a list to buy. Driving the cart while using the phone one-handed was not an issue with the 5s but I felt as though I was flirting with disaster trying to do the same with the 6+.
Having the phone in my pockets was another issue. I like pants that fit nicely but nothing like skinny jeans. I typically wear slim fit Dockers which fit more loosely than the average blue jeans and I found myself having to remove the phone from my pocket if I was sitting down at the desk. It was very uncomfortable to carry the 6+ in my pocket in a freshly washed pair of blue jeans. Once they loosened up, it was bearable but not unnoticeable like my 5s had become.
In the end, I exchanged my 6+ for a 6. While I do find myself pining for the larger screen and bigger battery, I am much more satisfied with the 6. While it is still more of a chore to use one-handed vs the 5s, I can thumb all of the way across the device to the upper right without stretching my hand too much.
