1. Notifications - the new UI is bizzare - rounded edges and the name of the app atop every notification is a enormous waste of screen real estate. Clustering notifications from the same app is an absolute no brainer, and should have made the cut. Ever since iOS 7, I am increasingly more skeptical of Apple's overall design philosophy.
The new notifications need some work. I will agree. They need to go back to the iOS 5 notification set IMO.
2. Control center - Still not customizable (this is next level arrogance), and if that weren't enough, iOS 10
adds an extra step to get to 'now playing' - which was my most frequently used feature (thanks Apple).
Control Center DEF needs to have some sort of customization. I dont use timers and wish I could change that to get to the clock. Wish I could change airplane mode and Portrait Orientation lock as well. Dont use them.
3. HomeKit - why does it come with those two ugly wallpapers? And why is there no option to choose from existing system wallpapers or just use a plain background?
This I personally couldn't care less about seeing as I dont use it. So its gone on my iPhone
4. iMessage - Apple seems to have completely missed the memo here - all this time and effort to enhance iMessage with juvenile features - why? Nobody in their right mind will ever use iMessage because its not cross platform by design. WhatsApp, Facebook Messenger, Line, Hangouts are far better, far more optimized and far more widely adopted alternatives.
Actually, quite a few people use iMessage. As a matter of fact, millions upon millions do.
5. Maps - who cares right? This effort should be completely abandoned - I don't know a single person who prefers Apple Maps over Google Maps.
I actually use Apple Maps over Google Maps locally. As a matter of fact, I havent used Google Maps in FOREVER. Reason being is because of the Apple Watch
6. iPad UI - hasn't anyone at Apple realized that you can't just blow up smartphone UI designed and use it on a tablet? I mean, has anyone seen the size of control center buttons on an iPad? Notifications and control center on the iPad need to be redesigned to make better use of the extra screen real estate.
I personally wish that the iPad would be a cross between iOS and OS X. But they DEF need to better tailor iOS to the iPad more. So much wasted space.
7. Mail - Probably one of the worst mail apps on a mobile OS ever - unreliable, and painfully slow. There hasn't been one instance where I've been notified of a new email and its
ready to view when I open the app - which hasn't changed in iOS 10. I must say the new filters and mail organization tweaks are most welcome.
Dont use native mail. As a matter of fact, I use Email by Easilydo. If you havent seen it, check it out.