While attempting this question in Old GRE Walkthrough videos, Greg mentions that the first blank cannot be predicted without reading the whole sentence. But can we not apply math strategy here right at the start? “It is puzzling‘ creates a contrast (-); Jones’s novel has been criticized has a negative connotation (-); so shouldn’t the next idea (and therefore the blank) be positive?
You can criticize something for any reason—is the novel’s structure too rigid or too loose? We don’t know the nature of the criticism, just that the criticism is seen as odd to the speaker for some reason (that is clarified later in the sentence).