To get back to the original question. Is this a good photo to use to paint a portrait from? I would have to reject it because the subjects do not interact therefore a painting done from it would not communicate anything.
The test of whether a painter is great or not probably doesn't happen in their lifetime so I would not presume to express an opinion on any living artist's work.
As for all the other discussions in this thread, all I can suggest to those who visit this Forum is that they read and read. I have spent years obsessively studying classical portraiture techniques and I have achieved a far greater understanding of the subject over the past few months since I have been visiting this site.
Cynthia, I have done many searches of the web and still haven't found a site which comes anywhere near this one for quality of information, classy appearance and ease of use. You may not paint portraits but you are an artist nevertheless!