I think its pretty apparent from the huge user feedback starting from the very first build of Win 8 all the way upto RTM that normal people do not feel comfortable with this UI. No amount of 'just use it and you'll like it' is going to change that.
It's only human that the first time that see or experience something is when we are most apprehensive and least knowledgeable. Over time by training, study and trial and error we become more comfortable and capable.
Desktop usage IS radically different, unless you discount such things as the start menu, charms bar, settings strewn all over the place, and a learning curver.
Do users spend most of their time with the Windows shell or in applications? I think that the key question in determining just how radical the differences are in the desktops between 7 and 8. The more time one spends using applications on the desktop the less radical the changes are.