There is no huge learning curve, very minimal for the desktop user. The App called "Desktop" takes you back to your Windows 7 usage. if you want icons on your desktop to make it easy to launch applications, then go for it. The task bar can still pin. Aside from going back to the Start screen to open a different app that you did not add to your desktop or pin to your task bar, then there is no real big difference from a user experience perspective.
I think everyone is just making this too huge a deal. If you don't like the new UI for the App side, skip it, stay on your desktop and pin your everyday apps to your desktop and/or task bar and be done with it.
If anything it will be a pain to Administer for IT departments unless MS give us some very good GPO controls!
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