http://en.wikipedia.org/wiki/Ribbon_(computing)
I find it (ribbon interface) better than those toolbar driven interfaces with miniscule 8x8 px icons where you have to make your best guess. In Microsoft Office it works very well.
I stuck with Office 2004(?) rather than upgrade to the XP-ribbon package. The odd day of working despite it while hotdesking on someone else's machine was enough.
I simply never used the ribbon - I'm sure it works well for what it does, but as I knew the relevant 8x8 pixel icons in word/excel at a glance (although I knew where they were anyway so rarely actually looked at/for them), they worked 'fine for me.'
My problem is not with the user interface design per-se, but with having fundamental changes foisted upon one which disrupt an established workflow. Changing menu entry locations/tree structures (and therefore the keyboard combination/sequence which activates it) between versions is a prime example.