There are two major areas of "improvement:" enhanced display/GUI, and a lot of security features. What MS failed to provide was a new file system to replace the older versions, or any critically new and compelling features (unless you consider the security features critical).
The other side of the story is that there does exist, as with any new versions of Windows, compatibility issues with some applications (certain ISP software, for example), and so on.
Almost all businesses are taking a wait and see approach to upgrading, and will certainly wait until---at least---SP1 is released for Vista. We have several computers at work loaded, and are spending a lot of time testing them with the various applications and mainframe programmes we use. I have not been so impressed with Vista that I want to run out and buy it and be a Beta tester for MS.
Edited by jgweed, 19 March 2007 - 08:24 AM.