I've been willing to give the Mac BU the benefit of the doubt, and Office 2004, while far from great, is an Ok product, but this new 2008 version is a crying shame.
How an intel native product manages to be noticeably slower than the previous version running in Rosetta emulation is beyond me.
And don't tell it's my machine, because I have seen this slowness on several different machines. PPC machines crawl as well. And I'm not alone, it's all over the web. It's not just the startup times either, calculations in excel, even the simplest of charts take much longer to create.
So save your money people. Unless all you do is look at an office product, this new version has little benefit and will actually slow you down.