The home page did not validate.
Nope the second page The form input element didn't validate either.
I would rate it an 6. Upon arriving on the home page there's really no indication what or where to go. There are links that if you start clicking you can figure it out after a couple clicks though.
I'd give the site a 5 for usability. Once you figure out what's there, it has a lot of information and resources available. The problem is figuring out what's there.
I would say that it meets it's purpose. Just not intuitively.