Jensen Harris, the Office 2007 User Interface guru, writes about what will happen to Office 2007 beta until the final release which contains a number of interesting gems.
One of the first stuff I found out when using Office 2007 (Word, Excel and PowerPoint) was that the system menu was gone from the upper-left corner, sorry Jensen I mean Northwest corner, so I could not double-click to shut the application down, and that I had to use the cross in the Northeast (upper-right) corner, introduced in Windows 95. This feel like a big issue to me, since I am used to it, and my mouse cursor is most often located to the left part of the screen, so I am a Windows 3.1 lover, according to Jensen Harris.Instead of opening the system menu you get the new Office File menu in the new user interface.