I know its a matter of opinion but for me I see iOS 10 as a huge step backwards in terms of usability and consistency with the design language as a whole. It feels like every update has a new font and a new font size. Small inconsistencies with navigation design make a massively disturbing experience for people to adjust to. The notifications for example - legibility has been reduced in my opinion so that my wallpaper can shine through without being dulled. And why oh why are app names force capitalized in the notification header! Its small subtle clues like the capitalization of app names or the color of the icon etc that help map short cuts in our brain and reduce fatigue and stress in daily repetitive tasks like the ones we do every day on our iPhones. Apple literally wrote the book on user interface design and in it they focused heavily on function over form. Great design is all good and well and often a matter of opinion but usability has much less room for interpretation. It might seem like nitpicking to some, but in my opinion this kind of stuff is important - it has a real measured effect on people lives. I thought with iOS 9 we were finally making some progress, learning from the disasters of iOS 7 & 8, but sadly no. Instead we take another huge step backwards.