- Substantially poorer performance
- Keyboard is less accurate
- YouTube videos can’t be played on the lock screen without some tricks
- Apple Maps (it is basically at parity now, however).
- Translate feature doesn’t have a copy button
- The storage bug
- No option for manual cache clearing
- SMB protocol doesn’t work with Windows and doesn’t display error messages
- File transfers are substantially more complicated than they used to be because they want you to pay for iCloud (the workaround here is installing VLC which gives you a drag-and-drop folder you can use through iTunes)
- Multitasking (apps should shut down after some time spent idle, instead they have to be manually closed)
I haven’t used the most recent versions of iOS so I don’t know if some of these have been addressed.