I think it really marvelous.
She's a verb short of a full sentence, that one
P.S. Although David Isaacson means it a bit critical, I think it has a tremendous descriptive flair.
"Gordimer's sentences are frequently a main verb short. The opening line - "Only the street-sweeper swishing his broom to collect fallen leaves from the gutter" (full stop) - is a sign of things to come."