I've always thought that Renoir was a brilliant draftsman and that everyone else would think so too. But it's by no means a universal view, and in the end it's a matter of taste and how different people define drawing. In fact there's no universally accepted definition of drawing, and it's futile to devote too much time to thinking about it.
However, it's important to me personally to have my own understanding of what drawing is, and especially what good drawing is, because otherwise how do I know what I'm striving for, and whether or not I've achieved it?
These are the criteria I use to judge drawings, my own and others:
Unity. Everything in nature has intrinsic unity. If the unity is disrupted or broken the object ceases to have life or to be itself, or the drawing is not convincing. Unity in a drawing is easiest to see in figure drawings, especially hands, and in animal drawings; but there's unity in everything, including landscapes and man-made objects. For an example of a lack of unity, imagine a drawing of a flower pot that looks as if it's made of plasticene.
Balance. I've blogged about balance in drawing before (A sense of balance). The kind of balance I mean relates to the law of gravity and it can be sensed or felt with one's own body rather than seen. A lack of balance in a drawn or painted figure or object is to me a fatal flaw, especially if it's my own drawing, unless there's a compelling reason for it to be like that.
Three dimensional form. A drawing that gives a solid illusion of three dimensions on a flat surface is a beautiful thing to see. Dark and light tones (or "shading") can help to achieve it, but there's more to it than that because a seemingly flat silhouette, or a simple contour, can give a convincing sense of three dimensional form with no shading at all. What it means is that drawing is a more complex and mysterious skill than at first it seems.
Life. Achieving a feeling of life is tied up with unity, balance and three dimensions. There's a magical quality about a sense of life in a drawing or painting, and if the work has life, then other shortcomings might be overlooked.
Renoir's painting of Mlle. Lacaux has all these qualities -- unity, balance, three dimensions and life, satisfying all my criteria. I wish I could draw like that.
Oddly enough, Picasso's sketchbook drawings of invented "creatures" (links below*) satisfy all my criteria too. The fact that they have 'life" is especially remarkable because these particular drawings are of invented inanimate clunky objects which could be carved from wood or plaster.
Some of Picasso's invented forms from 1927:
(first link, bottom of page; second link, top of page)
Some of Picasso's invented forms from 1933 (titled "An Anatomy")(first link, bottom of page; second link, top of page)
*Edited 17 June 2013: Those links were to The Online Picasso Project website which sad to say has since been closed to the public. Neither can I find those images anywhere else. It may be worth tracking down a copy of the big book by Carsten-Peter Warncke and Ingo Walther titled "Picasso" which has more than 700 well illustrated pages. I don't think the sketches referred to above are in it but there's a chapter in the middle called "A Juggler of Form", starting page 305, which has a variety of his other inventions.