Information Security Magazine has a very positive review of enVision in their July/August 2008 issue. The closest link I could get is:
you can also drill down to it by going to http://www.infosecuritymag.com. You will need to become a "member" to view the full article.
Here is the "Verdict" section:
"EnVision is quick to install, easy to configure, and will bring most organizations a deeper, more complete view of their environments."