Doesn't the OS have to work in order to learn it?
The Music app is broken, playlists at times play random music from other lists. iTunes Radio locks up the app and sometimes causes the phone to reboot. Opening the music app sometimes causes the phone to reboot.
AirDrop does not work 100% of the time. Getting it to work is really hit & miss.
Color scheme ripped from Windows 8, which very few actually like the Babies R Us theme. Part of the problem is it tends to give a fuzzy/blurry look to the entire device. For light sensitive people it just causes migraines.
Safari crashes or doesn't always load video
Music videos don't play fullscreen.
Keyboard is inconsistant most of the time it just picks the letter next to the one you typed. Or if it's on a white screen the grey is to light and bleeds into the white making it difficult to see.
Battery life is Droid level anyone with a variant of the 5 model needs to carry a charger.
iMessages only work for 50% of the people.
Sounds are inconsistent and don't always play on the notification center.
Music controls on lock screen move with the screen and unlock the device unintentionally.
No unlock sounds for the blind using voice over commands.
Mail app crashes often.