I have a lot of debates at the moment about how hard it will be for people and companies to adjust to the new release of Office. The first discussion usually surrounds the new user interface and how different it is. I'm not going to go over all the reasons behind the contextual approach again. The research in our labs, and this matches what I observe with the people I know who start using 2007, is that it takes between 2 days and a couple of weeks to feel at home in the new user interface. Now this is NOT how much downtime each user suffers making the transition, it is the time it takes for them to feel as confident with the new release and to take advantage of the new usability.
It takes a while to start to think contextually about what your are doing if you are very used to the Microsoft "menu mining" process. Sometimes the ribbon will switch the tabs for you and other times you have to drive that as you decide which aspect you are authoring. The other common gotcha is things on the Office transformer in the top left where "file" used to be. Everything to do with the document itself like saving, publishing, sending, proofing, properties about the document rather than the content in it, is based off the Office logo in the top left. This is a lot more logical. The trouble is that we have become conditioned to think illogically by learning the menus of by heart. One rule of thumb is if you can't find it, try the transformer.
At first glance, the ribbon approach is radically and perhaps scarily different. There is definately a "blimey! what do i do now" moment as you first open your first ribbonised 2007 application but there are also a lot of elements which remain familiar. For a start all the icons are the same as they have always been. All the main key strokes that you may be used to (things like ctrl B to bold etc.) still work. Some critics have said that we do not go far enough in our results oriented approach. Take the ribbon away, they say, and the authoring experience is still the same. The document-centric model is still there, right click context, drag and drop etc. all works as you have been used to.
An excellent analogy offered to me by a smart analyst who has been using the beta was helpful. He compares adjusting to the new UI to the experience of driving a hire car out of an airport. You don't know the car you will get. Some things are in different places in the car, it feels a bit funny and the visibility is all different. You can take a while to get confident driving it even though you are a confident driver at home in your own car. The part where you get in and drive it slowly around the carpark, trying out the indicators and window wipers, accidentally tooting the horn and getting the feel of the brakes and gears. This is how it feels getting used to the new Office but soon you drive out of the car park and you are on your way. It doesn't take long and before you know it, you have adjusted. Sometimes when you get home again, your own car feels weird showing how you made the switch. This is how it feels if you use 2003 after using 2007 for a while. They call it the "sense of mastery" which is the feeling that the application is on your side and you know how it works.
If it all goes wrong and you really can't find your favourite feature the Office online animations are fab. These give you a mock up of 2003 UI, you click on your beloved feature and it switches to show you where it is in 2007.
Word 2003 to 2007 Interactive Command Reference Guide
Excel 2003 to 2007 Interactive Command Reference Guide
PowerPoint 2003 to 2007 Interactive Command Reference Guide
There are also an impressive and growing list of training resources which give you bitesized lessons which companies are free to reuse. Books like this one are also great companions (under a tenner) if you are trying the betas.
Oddly enough, it is the people who are experts in 2003 who find the change hardest. We can get so trained in the Microsoft menu system that it is hard to think in an objective way. People quite new to Office or at a novice level adapt to the new UI and find it very intuitive.
Change does take some investment but it does pay back in spades. I guess it is the classic "sharpen the saw" decision. Do you keep on sawing with an old blunt saw or take time out to sharpen it which makes you much more efficient and pays back in a short period?