This is a good interview with Chris Capossela, VP for Office Marketing.
This quote does reflect what we have seen in the Access world. Although, you can argue that the Access change is even more dramatic as we changed the nav pane, introduced tabs, revamped getting started, and introduced layout mode for WYSIWYG form/report design.
“There are two data points that we talk about. No. 1 is, for your average Office user, we see that it takes them about two days of working with the product before they say, "I'll never go back." For your power user -- the people who know the ins and outs of Excel, maybe the finance team, or the legal team when it comes to Word -- it takes them more like two weeks before they'll say, "Please don't ever take this away." And that was a little bit counter to what we first thought. We thought the more casual user would be more scared, and instead, it actually turned out to be the more die-hard user, because they know exactly where everything lives in the old version. So it takes them longer. “
Chris also points out that we have extensive online training resources to help ramp people up and this version was downloaded by 3.5 million people. Here is a link to the Access training session http://office.microsoft.com/training/training.aspx?AssetID=RC101933201033.
What Chris didn't mention from the Access perspective is how many new templates have been downloaded. So far, that number is around a quarter of a million. We have found providing a good template dramatically helps new and power users start being productive. I will post more about that in the future. We have an update on the way to Office Online.