What do you like best?
This works well on a big picture and granular level. Look at vulnerabilities by severity, by type, by name, by device, etc. This lets you do targeted pushes to minimize threat surface.
What do you dislike?
The lack of playbooks or other automated remediation of vulnerabilities and threats is the biggest weakness of Tenable vs. its more robust (and costly) competition. The product, because it isn't using machine learning, is purely reactive. This is limited to, effectively, from-the-inside-out scanning, it does not really look at your attack surface from an external perspective, which is the perspective most potential attackers have.
Recommendations to others considering the product
How mature is your Security team? If you have the right people and processes in place to be able to execute patching and vulnerability remediation at scale with where you already are, then Tenable is a fine solution. If you don't have this in place yet, get it in place before spending on a tool. If you can already do this in your sleep and are highly motivated and skilled enough to develop your own automated remediation playbooks, look to a solution that can do more of the heavy lifting for you.