One of the most beautiful things about the open source / Linux world is that you rarely have to learn a new way of doing things, unless you want to. Prefer Gnome 2? Fork it. Not flippant advice -- enough people preferred it that a new community project started. So you can still run the desktop environment you did 15 years ago. That's simply not an option - no matter how many users might want it - with Windows should Microsoft make a decision about the direction of Windows. You will spend time and effort relearning after forced changes.