The usability of Office before the Ribbon vs. the usability of Office after the Ribbon is like night and day. It was a massive overhaul, and it was for the better - the product is, IMO, far easier to understand.
It's a huge innovation, and frankly I think it's silly to discount it as a "coat of paint".
It's that hard to believe that I think one of their latest innovations sucks? I use Excel on a regular basis for simple regression analyses and data shuffling.
No, people hate sudden change. When it comes to more gradual change, such as the user interface progression from XP to Vista and then to Win 7, it is totally fine. But going from Win 7 to Win 8? Not so much. (Yes, Win 8 will have an old-style UI option, but that's not the point.)
It's a huge innovation, and frankly I think it's silly to discount it as a "coat of paint".