The New York Times called Doctorow "a leading figure in contemporary American letters" who "situated fictional characters in recognizable historical contexts, among identifiable historical figures and often within unconventional narrative forms....
"Subtly subversive in his fiction--less so in his left-wing political writing--he consistently upended expectations with a cocktail of fiction and fact, remixed in book after book; with clever and substantive manipulations of popular genres like the Western and the detective story, and with his myriad storytelling strategies. Deploying, in different books, the unreliable narrator, the stream-of-consciousness narrator, the omniscient narrator and multiple narrators, Mr. Doctorow was one of contemporary fiction's most restless experimenters....
"His protagonists lived in the seeming thrall of history but their tales, for the convenience--or, better, the purpose--of fiction, depicted alterations in accepted versions of the past. Not that he undermined the grand scheme of things; his interest was not of the what-if-things-had-gone-differently variety. Rather, a good part of Mr. Doctorow's achievement was in illustrating how the past informs the present, and how the present has evolved from the past."
And at the BBC
And at The Guardian