UI of limited choice
I clicked on the upgrade link in Windows 10 my initial impression, the first 5 minutes, was seems OK but probably unnecessary. Then I tried to customise the task-bar only to find it cannot be placed to the left or right. As the registry hacks to fix this where ignored or automatically rolled back I hit the revert to Win 10 button without delay. Probably the smallest of the erosions of freedom from MS but enough to put me off for a year or two.