Personally I quite like using it. I too heard the message that most feature requests for Office were for features that were already in the product. There's another aspect of the Ribbon that I don't think has been commented on here: end-user customisability, or the lack thereof...
We developers can customize the ribbon in Office apps, of course. But users actually can't. Remember the command bars in Office 2003? Of course you do. Again, we quite like ability to drag them around and add/remove buttons from them. But for most users this was a real problem. It was far too easy to accidentally drag a command bar to a different part of the window, or to remove buttons unintentionally. Apparently, a huge number of Office 2003 customers reported having to re-install because their "save" button had disappeared.
In the ribbon, the only end-user customisable UI is the so-called "quick-access toolbar" which normally grows from left-to-right along the title bar of the window. This could be an annoyance for power users, but should lead to fewer support calls.
Developers modify the ribbon in the Office apps via an XML definition. This can be supplied in add-in code, a VBA macro, or even in an Office document (the new packaged XML kind). That's quite neat, and leads to new possibilities: I could create a form in Excel for example and email it around with a custom ribbon definition. People who open my document can't access any of the normal features, but can see my custom ribbon buttons, that maybe invoke some macros. I dunno, I've not done it in anger, but it might be useful for someone.
I've never really understood why 3rd-party apps feel the need to copy the Office UI. After Office 2007 launched, there was a rash of lookalike Ribbon controls from all the usual control vendors. To my eye, none of them does a great job of mimicking the "real" ribbon. It seems to me that if/when the package comes along that defeats Microsoft Office, it won't be by copying the Office UI. So I reckon it makes sense to think about the right UI for your app rather than blindly adopting the ribbon. Microsoft themselves have said that the ribbon makes sense for those Office apps that contain a huge number of discrete function points, but not for those apps with fewer.