What other disadvantages do you ascribe to it?
My main objection is that it provides no serious advantage over menus, it's hard to find the things that are used less frequently, it changes dynamically, meaning that I often have to hunt around to find the item I need rather than knowing exactly where it is no matter what, it's cluttered and visually confusing, it requires configuration to become remotely usable, and so on.
It doesn't take up meaningfully more space than the menu bar would (it takes significantly *less* space than a menu bar plus a single toolbar)
Not on my machines. I'm looking at the ribbon in Outlook right now, and it take up three times the space that a menu + toolbar does.
it scales to multiple resolutions and window sizes better than menus do, it makes it easy to see what the effect of an action will be before you click
I disagree with both of these assertions.
A lot of this (maybe most) boils down to taste, so let me just leave you with my #1 objection: I'm much less efficient working with the ribbon than with the menus. The ribbon just gets in my way.