Ribbons
That Ribbons interface actually looks pretty good on OS X. They seem to have found some balance between OS X (menu bar) while still bringing in the Ribbons UI. (I understand it is well thought of in the Windows community.)
As others have noted, it does look kind of cluttered, but I might be able to get used to it. I'm sure we'll be able to fiddle with the interface if it isn't done by release. I'd like to get rid of the text ("New", "Open", "Save", "Print", etc.) and shrink the toolbar icons down (if not get rid of them completely).
One thing that I like about the current Office UI is that since everything is in a floating palette, when you switch to another app the only thing showing from Office is the current document (no controls like Save, Bold, etc.) This saves screen real estate, and lets you look at the document while working in other apps. With this new Ribbons interface, this would (probably?) all be thrown out the window. (Maybe it the Ribbons shrink down to nothing when the app loses focus, but that might be too clunky.)
The other possibility would be there could be the option of putting the toolbar and the ribbons into their own floating palettes. I would probably like that solution best.