I've adapted to the ribbon on Word or Excel, and with screens as high as resolution as they are, the wasted space is annoying, but fine.

However in AUTOCAD, which has hundreds and hundreds of commands, it's just silly. Blocks of icons are fine for those oft-used commands. But for the rest of them, ones that you use once a week, month.. year, a list with a short description is what you want. In fact, many commands simply aren't in the ribbon at all unless you add them yourself. So the fact is that with the ribbon I find myself using the GUI less and the CUI more. That sounds like a failure of a GUI to me.