A post on Groklaw gave a link to a blog of Office 2007 screenshots, and a lot of interesting discussion followed. A surprising number of Groklaw readers liked the interface, given the reader bias, and the amount of (and extent of) retraining required for the new interface was a hotly debated.
I tend to side with the reports of experienced sysadmins and IT heads here -- users hate change, and frankly, there's nothing new under the sun in the wordprocessing and spreadsheet worlds. Most of what I see in the new Office is change for change's sake. MS is already facing an uphill battle convincing IT departments to upgrade all their machines to a new version of Office when users aren't complaining that current versions can't do what they want, and that would be even harder if the new version looked and felt just like the old version.
Sometimes, conformity is a good thing, and user interface is definately one of those areas. There are 11 applications running on my Mac, ranging from Mozilla to Skype, and all of them save one have "File" and "Edit" menus.
There was a split on Groklaw between "power users" that thought that it was new and interesting, and wouldn't have any problems picking up a new interface, and "normal users" (or those who support and deal with normal users) who just saw it was different, and therefore a pain in the ass. Having had to coax Katie through the process of learning OpenOffice, which is far more similar to Office 2003 than the new version is, I predict hearing from lots of normal users repeating the old mantra:
"If it ain't broke, don't fix it."