"Issues" is a broad issue! ; )
I ran the 2003 beta in an office that also uses Office 97 and Office XP, and
only encountered one problem with Excel that was corrected in a subsequent
beta update (I'm still running the beta). I encountered no other
compatibility issues. File formats remain the same, with the exception of
Visio and Outlook which have slight changes to their data formats. However,
both are 100% backward compatible and can be set up to run in 2002 (XP) file
compatibility mode.
Randall Arnold