If ever you are deploying a solution, if it be a personal solution, private, or for a client. It helps you make sure that your solution conforms to Patterns and Practices as well as .NET Guidelines.
I recently found this out the hard way when one of my solutions did not pass the checks that FxCop performed.
In any event, this is a great tool for you to pick up any errors that testing might not, and to help you make sure that your solution adheres to best practices of Microsoft, and .NET Framework guidelines.
Documentation can be found here
Available for Download here
This tool has helped me immensely and I now see the error of my ways. I hope that you do to.