Some things I truly hate:
-the new cursor sucks like mentioned before
-the dialer hidden underneath call history app. You should be able to pin the dialer to startscreen Jesus Christ it is a phone and this dialer is hidden!!
- that I can't remove games app and other stuff I don't use
- settings have no logical order
- copy and pasting sucks. It always forgets what is in the clipboard after a while
- inconsistent notification layout for different apps. Skype users two lines and WhatsApp shows all on one line
- agenda showing am/pm while I've set 24h format :/
- agenda showing only one item on the tile
- SMS confirmation shows number and not contact name
- the too small spacebar on keyboard
- resuming
- no alarm time to be seen on lock screen when I've set an alarm
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- not getting notifications from system app updates like display and glance
- no data toggle, no 2g/3g/4g toggle and many more missing toggles
- too few notification icons allowed on lockscreen
- no app list sorting like in w8.1
- max amount of members in groups is ridiculous, you can only make tiny groups. Should be unlimited. Now I must make companies1 companies2 companies3 ******* dumb
- no way to grab the scroll block and scroll faster
- no way to set wifi priorities
- time sync over internet doesn't work
- backup is unreliable, never managed to get my strartscreen back
- no IRC app that can run in the background, probably a missing api
- and a whole lot more