Have to agree more and more.
IPhone 7+ - have gone through two complete reset as new. It’s slower, battery 70% of iOS 10, appointments don’t always show in the calendar, load delays with stock email, RAM manager problems (app/tab reloads), double sound alerts in iMessage, etc ...
IPP 12.9 G2 - reduced battery life, freezes in Safari, iMessage alerts intermittent, GUI slower, etc ...
I have become used to growing bug issues as iOS evolves - which should not be the case - but it is like iOS 11 has reached a new level. Not sure where I go from here. I dislike the design, and price, of the X.