Daniel Green at The Quarterly Conversation:
The Overstory displays some of the formal and stylistic ingenuity we have come to expect from a Richard Powers novel, from his acoustically adventurous prose to his multiple, intertwined narratives (even more multiple in this novel), so characterizing it as purely “agitprop” would be neither fair nor accurate, although the novel is certainly transparent enough in its effort to promote environmental mindfulness. And since Powers has always been willing to take on the weightiest of subjects, generally treated in an earnestly sincere manner, it would go too far to call The Overstory sentimental, although the passages invoking its characters’ often rapturous appreciation of the trees that threaten to replace the characters themselves as the novel’s true dramatis personae are surely full of passionate intensity.
more here.