Typing a letter, seeing the keyboard respond to show that letter was recognized... Then putting the phone down, making a sandwich, coming back, and finally seeing it actually make the key click noise and enter the letter in the input field.(That is not an exaggeration. That happened.) A day after that it turned into a brick and I had to give it that DFU middle finger to get my iPhone 6 back into a workable state. That was all because of the iOS 11 upgrade.(I skipped past 10.2.) While the full reformat of the phone has more of less resolved the issues it still experiences slow downs while rapidly draining the battery due to iOS 11 idiocy.

My phone's remaining battery life is above 80%.