It's not the ribbon system that irritates me--it's that many useful features that I used to use routinely are either missing or obscured far down the menu levels or irrationally placed. My Quick Access bar is already full with tools I use frequently which otherwise are buried deep and hard to find because of their irrational placement.

Here's an example of irrationality: Suppose you want to change the size of a text box and you get to the Format Shape panel. There are 3 shape options there, one has an icon that looks like the right one, but no sizes there. (Some irrelevant feature do exist there.)

Home (no Format option), select the text box to change (only then you get a Format option, but no format text box) Shape Styles (get the Format Shape panel), select the sizing-like icon: useless, only then see that the size tool is in the ribbon, not in the panel. Why not in both places? Infuriating!