The Alpine Club Guide Book grades this climb as AD and Gaston Rebuffat grades it as AD+. I think that the AD- grade given on this page is too low, because although the technical difficulties are not too great, the route is long and sustained.
The author is right to say that you must take two ropes, I took two 50m ropes and would have prefered 2 x 60m due to the spacing of the belay points.