Here is an example on the retina display with Office Mac on the left and Office running in Parallels 8 with the retina display enabled (Windows 8) on the right.
Excel: Definitely can see the fuzziness on the Mac version. The Office version looks gorgeous.
Outlook: The Office Mac team actually upgraded it to a Retina app, so there is no fuzziness. However, the font choices on Windows just look so much crisper than Office Mac’s fonts. Also, Outlook on the PC is just a lot more mature and feature-rich than the Mac version.
Outlook Calendar: Retina on both. Design style differences.