My Air 2 is absolutely performing flawless. But I agree, I’m actually holding out to see if we have a spring Keynote that will release an updated iPad with Face ID. But given that the iPad Pros just refreshed in June 2017, at the earliest for an iPad to refresh with Face ID, would not be until this Fall.
Same here, all things considered the iPad Air II has probably been the best Apple product I've ever purchased from a standpoint of longevity. Bought in October of 2014 it's going into Year 4 performing as quickly as it did on Day 1. Pretty amazing.
Still afraid to update to iOS 11, it's great on iOS 10. But the lack of Face ID and the missing X gestures are annoying and I need an iPad that includes them.