As reported by Forbes and TechRadar, among others, the battery life takes a huge hit with iOS 11. If that isn’t a deal killer by itself, a few of my favorite apps no longer work yet I was given no warning prior to upgrading. This is Software Development 101 - if YOUR ugrade will break existing applications (certainly those as popular as Adobe PhotoShop Touch!) then it is YOUR responsibility to warn your customers. My last complaint about Apple updates is that too many changes are made to the interface for no discernable reason. Keyboard is just one example. Another is the notification screen getting in the way of productivity apps and games. I can usually turn off the Notifications Hijack (as I consider it) but why should I have to take that step when my Settings were already chosen?!
Apple: If it ain’t broke, don’t fix it!