If you want a better idea of what using Office's new interface is really like, I recommend this streaming preview video (direct link to WMV stream) that Microsoft has put together. It's a 13-minute marketing piece so be prepared for some awkward scripted dialogue from Real Microsoft Employees (Dear Product Manager Julie Larson-Green: The camera is over here. Please look at it.), and unless you're a corporate executive you'll probably get the gist of it in the first five minutes.