I just want to say that I _like_ the new ribbon interface. Opposite to MS Office, the Ribbons are clearly structured and it is easy to find what is needed (at least for me)
OK, people who used customised interfaces have to do all that work again, because of incompatibilities. This is awful, but such things happen. Remember the old times, when MS completely changed the format of backup files between DOS 3 and 4. People who backed up their systems before upgrading from 3 to 4 weren't able to restore afterwards.