The “Ribbon UI” (what I would call the “Tabbed Ribbon UI”) is miserable. It’s been miserable since they rolled it out in Office 2007 and makes me dread any new office products . Microsoft threw out interface conventions everyone was comfortable with and then introduced a brand new user interface that requires significant learning for experienced users to access common features. Even more frustrating is that one tab can have it’s own separate ribbon format and orientation (the e.g. the File tab in Microsoft Office). New and old users were all new to the “Tabbed Ribbon UI” in 2007 and they blew it. I also work mainly on a notebook at home and that means already limited screen space is wasted by a bunch of commands I never or rarely use placed to obscure all the commands I like use often.
It was enough to permanently move me to try other Office suites (Open Office and Google Docs). I use Google Docs and now I only use Microsoft Office sparingly at work (Excel and Word) and occasionally at home (say on the rare occasion someone only has Word and needs a document from me). With additional scripting capability added to Google Docs, I am extremely comfortable using it as my main Office suite.
As long as the “Tabbed Ribbon UI” is implemented in the current fashion, I will continue to use Microsoft Office products less and less.