I just got my hands on Microsoft Office 2007. My first impression about it is very positive. Its very slick and nice. The UI is very refreshing and easy to use. And its faster and intelligent. I've tried just the Word, Excel and Powerpoint till now. Saving Powerpoint to pdf is very nice. It needs a plugin to be installed. Its not obvious why they didn't include it by default.
Although the installation took a lot of time, it was very easy and asked few questions. It detected and upgraded my Office 2003 installation.
Outlook 2007 still sucks. Nothing much different. Too slow and still hangs with IMAP over SSL.
Probably I post a more detailed review later.
Once again, Microsoft has made sure that its stronghold office presence isn't threatened by any other Free or commerical offerings.