I like that they do both deliverable/deliveries as well as spam score for all of our domains, which helps us make better decisions about where to focus resources in improving each domain's SPAM scores (or not).
The interface can be confusing at first glance - there are so many options it takes some time before you get used to them! If your organization has multiple sites with different content management systems or if your customers use other applications such as Gmail then this service mayβ¦