A strong Content Management System must be accessible to as many people as possible. One of the areas that doesn't get much attention is that the CMS you choose must be easy to use. If it isn't, why bother to have one? A good CMS will not stand in your way of producing great content for the site; it will not complicate the process, only improve it. After all, the content is who you are, and you won't want to fight the tool to get things done.
In my opinion, a great CMS will allow people at all levels of your organization to participate in the creation of content on the site. That being said, you need to make sure your CMS also has a robust workflow engine incoroprated so that it streamlines and matches any processes you already have in place.
These two specific areas in which Plone excels particularly well as compared to other systems. Not only is it easy to use, but it is also easy to download and install from the download section of plone.org. Once the program is installed, anyone in your organization can contribute to creating your web presence and help generate content that will increase traffic.