Wow, what a discussion! As a Tech support person for over ten years and having worked with Word since version 6 (which came on a set of about 14 floppy disks) I've noticed a number of things.
I like the old interface for a number of reasons: it could be customized to just the way you liked it and it pretty much stayed that way, I had "toggles" so I could toggle on/off toolbars like the drawing toolbar which I frequently used, other infrequently used toolbars could easily be turned on/off as required if I was working on some project, and even the toolbars themselves could be customized. All my toolbars and their Icons were just a click away, now I have to figure out which menu I have to be in first and they're often 3 or more clicks away as I try to figure out which menu I need to be in.
As a company that had hundreds of templates, we had created our own toolbars for the most common ones: fax covers, letterhead, etc., that were always available - however they are now buried a level deep under the oddly named heading - Addins.
Odd thing though, even though we had pretty much a common user interface with everyone having access, I couldn't "teach" some of the users to use many of the common shortcuts - they would click "File, Save" or "File, Open" instead of using the first two or three icons on their menus - even with those menus being consistent across all of their Office products.
Now, with Office 2007-2010 they've renamed a number of functions which totally threw us off. Sure you could find "Insert, Page break", but to insert any other type of break you have to go to Page Layout??? Office seems to have gone from having 5+ different ways to accomplish a task to one.
Parts of the ribbon really are a pain, but I personally really like the way you can "preview" the way a document or paragraph will look just by highlighting a font, point size, or style. Unfortunately, that's not much use in our Office environment where 95% of the staff only use 2 designated fonts for filling in templates.
The ribbon is a nice idea, but not suited to the way most people work.
Any why did they change the reply to "do you want to save your changes?" to "Save, Don't Save?" when I was used to hitting Y or N??? But that's another topic...