I am a Ruf fan, in spite of the flaws in her methods and reporting.
Now, I would caution anyone and everyone to resist getting too worked up about the levels, just as I would caution people not to reduce a child to an IQ number. The levels are a tool. Tools are good for some jobs and utterly destructive for others. The levels don't work well at all for most 2E kids or for late-bloomers, for example. I find that very problematic and limiting.
But to jar a parent--like, say, ME!--out of gifted denial, Ruf's book is very useful. I thought DS9 was "just" moderately gifted, and we were prepared to spend years trying to jam the square peg that he is into the school's round hole, no matter how disasterous the results. Ruf's book changed all that for me. The anecdotal evidence of other gifted kids was useful to me because I could see my son in the children she described. I could see where he was "more this, but less that" than the kids she discussed. That was more useful to me at the time than test scores, which were just numbers on a page. Ruf's book brought the kids to life for me so I could understand levels of giftedness in a way I hadn't understood it before.
As a hard-and-fast way of nailing a kid's IQ or future achivement or whatever, though? Not so useful. And while I think she goes too far about what "must" happen for gifted kids, since personality matters a lot and all kids are different, I will be forever grateful to Dr. Ruf for giving me permission to homeschool from a pro when I needed it. Her book saved our DS9 and our family from all sorts of headaches and heartaches. I'd go so far as to say that it was life-changing for us.
With numerous caveats about its weaknesses, I still recommend her book to parents who seem to need a wake-up call, as I needed. More than anything else I've read about gifted kids, it serves that role. I wish there were better, less anecdotal research out there to fill that role, but to my knowledge there is not. It's not perfect, but it really, really helped our family!
As for the website, I think it's like the book in that it's a first step/wake-up call. It's a computer applying the lists in the book to a given child. Any parent could do the same thing without paying the money. I don't think it is anything definitive, nor is it really supposed to be, I suspect.
