Under normal circumstances, we recommend that you install software patches and updates (software upgrades are a different story) fairly close to when they become available. The reason for this is that most updates and patches help fix bugs and mitigate security vulnerabilities that have been discovered in the software.
However, at times, software vendors really get an update wrong. That's the case with the recent update released for Microsoft Office for Mac 2011 (that's 14.5.0, for those interested). A number of users are reporting that installing this upgrade renders Microsoft Outlook 2011 unusable. As in, you can't open Outlook to view emails and contacts, and you certainly can't send or receive email.
If you have Office 2011 for Mac, and use Outlook 2011 for email, we'd recommend holding off on installing the update until Microsoft releases a fix (which they undoubtedly will). Keep checking back on our blog for updates on the situation. We'll update this post to let you know when it's safe to apply the update.