http://www.dailytech.com/Windows+8+Early+Build++Explorer+is+Built+Around+Office+2007like+Ribbon/article21298.htm

pre-Ribbon: "It's worse than that. There was a Print button on the toolbar that by default was already there. One click."

Ribbon: "Window Button -> Print Context Menu -> Quick Print."

As you can see, Ribbon, producing 3 clicks from the user instead of 1, produces the most clicks. This I call a productivity boom (with a small sacrifice of abundant vertical space).

Further productivity is gained by customizing the ribbon and looking for said customizations in non-customized setup (should one not be aware of there being customizations present). This can be enhanced by distributing customized ribbons to all users, such that each organization has their own custom UI. (Of course IT should block each user from customizing their UI's and using their customized UI everywhere. Because support can't help with custom UI's.)

OTOH all that could be a bunch of FUD, as I haven't used Office much since quickly testing 2007 and going back to 2003. I'm worried about Windows 8 going the same way. This is of concern due to some issues that MS is unlikely to fix in Windows 7 service packs. If Windows 8 fixes some issues and adds a bunch of new Riblems then where does that leave us? Fuddity fud (fud).

(Of course, if you have a tablet, the Ribbon UI may be better in that context for Explorer use - but was it designed tablets in mind? If not then it's likely not optimal for tablets)