I'm interested to see what behavioural changes I'll make when I start using my 6 Plus together with the Apple Watch.
In and around home and work, I'll no longer need to carry the 6 Plus everywhere I go - as long as I stay within Bluetooth and/or wifi range, the Watch will tell me about key happenings.
Similarly, when I'm out and about, the iPhone can spend more time in a bag or pocket - as long as I have it somewhere on or around me.
The longer battery life will, of course, become even more important and appreciated when also using the Watch.
I suspect (hope) this may leave me even happier with my 6 Plus - but we'll see.