When first introduced for 2009 there was a sense of "Where did everything go?" and "How the heck am I supposed to use this?". Autodesk corrected in 2010 with an OOTB option for a "classic" interface during setup (it was there in 2009, just not in the setup), so as to help seasoned users hang onto the old while adjusting to the new.
The ribbon has its own quirks, but all in all, once you understand several things it is not all bad:
1. You still can have menus and toolbars, and the ribbon can be set to appear several different ways, including not so jumbo.
2. Using CUI it is all very customizable.
3. I think it pops faster than a toolbar flyout.
4. It is here to stay, thanks to its interoperability with other autodesk products and with Microsoft Office.
5. The intention is to put groups of related tasks together, but you can decide how to rearrange it for your groups of related tasks.