My 2nd generation iPad got so sluggish on iOS 9 that I will not take it to 10.
My iPhone 5 is on 10, I am still trying to get used to subtle and not so subtle user interface differences. I do like how some of my apps now put notices on the lock screen, but I need to work on which apps, and maybe within the apps, which notices. Traffic info is more useful to me than the most recent shootings or convenience store robberies.