I have iOS 10 on my Air2 and it seems to run fine. However, I'm not a power user. I just use a few apps and safari. No noticeable increase in app crashes or resprings. The new unlock screen is annoying, but not a major impediment. I only installed it because I have a very old app that I don't want to update to the newest version of the app. I wanted to check that the app would run in iOS 10 while I could easily check and downgrade if necessary. The app itself actually runs better than in iOS 9, but I get the occasional pop up telling me it isn't optimised for 64bit or iOS 10.