Like Smitty said, it's a pretty good port. The main stuff that gets queered up is if you had menu customizations or created custom toolbars using code. That will still work, but due to the new interface, it all gets dumped in a custom "Add-Ins" tab.
AFAIK, they only took out one object - the filesearch object. I can't think of any other code that would automatically raise an error. But if you use code to create charts, plan on needing to tweak that code.