This piece is worth watching as it develops - Jan Fitzpatrick at Thread Medley has now started a smaller piece for a bit of relief from the large rug adaptation she's been working on for a while.
You can go there and watch it almost from "day 1." Her explanations of how and why she does each thing is really a great learning experience, as well as very interesting. Beautiful work and beautiful colors!
I think a good term for these things would be "simple elegance."