Starting with The Corrections through Freedom and now Purity, Jonathan Franzen's ambition has continued to grow—at least in terms of the narrative canvas and palette of ideas he's exploring.

Alas, the formidable heft and scope of Purity seem to have gotten away from him and the book doesn't deliver the same seductive cocktail of story, style and intellectual provocations of his previous two novels. The writing is more pedestrian, to start, and the Luddite crankiness around the internet and social media that has littered his recent nonfiction writing and commentary undermines the book's believability, while the characters feel underdeveloped, more symbols than flesh and blood.

Of course, Franzen still spins a good yarn and the book is compulsively readable. But Purity doesn't really stick with you the way his previous two novels did.