1. iTunes is slowly degrading into a usability nightmare - recommendations are often albums I own and bought from Apple!
2. the OS itself seemingly picks apps at random for the "play" button on the "swipe-up" menu. Like I might play a podcast on, say, Monday morning and then switch to music - but for the remainder of the monday and some of tuesday when I pause, lock and then later use the "swipe-up" menu it tries to resume playing the podcast not the music. not to mention this menu has two tabs, and switching between them involves a swipe - which usually triggers some of the sliders (Brightness, volume, position) on the screen. This clearly didn't go through any UX testing.
3. no way to disable "voice control" home key shortcut - my iPhone 6S has an AWFUL habit of interpreting background noise as "Dial my ex girlfriend". I somehow can't kill the call before it starts ringing, but usually I don't see it because something has pressed the home button in my pocket. It's truly embarrassing.
4. "Do you trust this computer?" for the millionth time, yes!
This is my last iPhone, I think.