Have not read anything by her yet but intend to do that pretty soon.
In any case I found a snippet from the description of her literary style interesting:
Lessing’s fiction is commonly divided into three distinct phases: the Communist theme (1944-1956), when she was writing radically on social issues (and returned to in The Good Terrorist (1985)), the psychological theme (1956-1969), and after that the Sufi theme, which was explored in a science fiction setting in the Canopus series (see below). (for complete article about her: http://en.wikipedia.org/wiki/Doris_Lessing)
From communist, to psychological, to Sufi .. I find this movement very informative. It starts from youthful radicalism, when with our energy we zealously reduce social problems to specific themes and rally around them; then comes the psychological level – this often results from a realization that you could not change the world – where you attempt to allay your unrest; but that too fails and you are lead to the transcendental .. and that is where the journey ends.