After reading most of the thread I had to sign up you give my experience,
After receiving my launch day 6s plus was exited to check out the display especially coming from a 5s.
So I powered up the new device and was shocked at how dull , lifeless and slightly yellow the display looked and had to
power up the 5s to confirm my suspicions.
Not very long after maybe a few days the display looked way better and after a couple of weeks looked very close to my 5s.
I am not sure if my eyes were adjusting or if the display really had started to change colour.
Around the time Night Shift was introduced I noticed my display had a cool blue tint to it (Night Shift off) when previously
it was much warmer.
Again I am not sure if after using Night Shift (Very warm setting) and then turning it of again tricked my eyes making the display seem cooler.
I can turn up the Night Shift slider from cool to around a third of the way up and the display looks almost perfect to me and leave it on permanently, but then loose the benefit of sunset to sunrise option because I like the slider set to around three quarters up i.e. very warm.
Anyway I can live with the new cooler looking display, Its no better or worse just different.
Glad I got that of my chest.
Thanks for reading