US Military Uses Open Source CAD

Has anyone used the Open Source CAD program called BRL-CAD? Apparently the US Military uses it. The homepage is http://www.brlcad.org/. There is documentation available, more screen shots, and a project site. If you've been reading my Blog, you know that Open Source means free.

I don't know anyone that has used it. It would be nice to know if it's worthy being called a replacement for the expensive Auto-CAD. It's been available for the Windows platform since 2006. Maybe my buddy at Crystal Coast Tech has tried it? Comments please?