I didn't like the ribbon interface for a long time. Then I watched a video of Joel Spolsky doing some stuff in Excel and it was the first time I really saw somebody that knew what they were doing using the ribbon. That converted me.
No. Keyboard for the things i know by heart and use every few seconds, mouse for the things that happen from time to time, and explorability for everything else.
Also, link to that video?
Edit: I think you mean this: https://www.youtube.com/watch?v=0nbkaYsR94c
Very first thing i notice is he rides hard on the "Paste as Values" option being the one you want to use most of the time. However since he has the ribbon on top he has a gigantic paste button and needs to use the drop down every time to call it.
With normal toolbars you'd just add a "Paste as Values" button next to the normal paste button and skip the error-prone, slow dropdown process.
(I also note he has no keyboard shortcut for it.)
Paste as values: alt h v v