Here is one idiotic but simple reason why Windows 8 will have problems. I was at someone's house yesterday and was asked how to change the profile picture.
Seems simple enough. Go to the Control Panel, select User Accounts and change the picture for the account.
Nope. They pulled that option.
It is now in PC Settings in the charm "menu". Why?
Keep everything in one place!
Even better, if you want it in a new place, that's fine but leave it in the old place as well.
Like in windows 7 and before you could access the Device Manager from the Control Panel or right clicking My Computer on the desktop.
But to split user account settings in two?