Office 2007 is coming (actually, it's already here, but Siena hasn't adopted it quite yet).
I'm pretty impressed with the program. Items are designed in a fairly logical manner, and are simpler to find. Fewer mouse clicks. In addition, there are some really nice formatting options.
Microsoft has put together a nice quick demo of some of the changes*. The most obvious difference is the menu. You don't have the same options you've gotten used to in the past decade. Instead, there is a "ribbon" that gives far more options than previously. Instead of trying to remember what menu to click to display what you want, you can very often see it without clicking.
Most confusing is the Office Button. It's a little button at the upper left of the screen that leads you to the type of options you see on the file menu. Since it looks like a design element and not something to click on, people are going to find it hard to find things at first.
I also wonder why they don't put a print button on the top menu. You can add it manually, but normally you have to click an extra time to print.
But these aren't deal killers. They'll cause confusion at first, but after a little time working with the program, people will get the hang of them.
Here's a nice description of the differences between Office 2003 and 2007 (pdf). If you want to test out Office 2007, log on to Citrix (either through Program Neighborhood or via the web) and try it out.
*Though I wish they wouldn't sound so enthusastic about how the software changes they way they work; most people like the way the currently work and would prefer not to change, even if the result is better.