Most of all, it's an immensely tolerant novel - which is not the same as permissive. Billy's progress and intermittent regress becomes an eloquent plea for generosity of spirit. At the same time, there's a strong moral core, grounded in love and forgiveness. The only people Irving condemns are the intolerant and bigoted, those who shrink others to a "category".
There's a technicolour cast of oddballs, misfits, joyous renegades, all of them the stuff of light farce and dark despair. Don't miss the follically-challenged owl-ravisher, or the Scandinavian with the saggy syntax.
Irving-ites will not be surprised to hear that wrestling sometimes takes a hold on the plot. So does theatre, especially in the forms of Shakespeare and Tennessee Williams. No surprise either that Billy's first on-stage role is as the androgynous sylph Ariel.
He reads omnivorously, starting as a 13-year-old with Fielding and the Brontes. Later, as he travels through Europe, he reads all of Madame Bovary aloud to his lover. Inevitably, he wants to become a writer and he does so, successfully, while friends strain to find themselves in his stories.
The sexual match commentaries can become repetitive. The flawlessly recollected dialogue can become protracted. You'll find yourself wondering if quite so many participants have to swap genders; the associated surgery and hormone treatment may make your eyes water.
A big story from a big writer. There's raunchy, rueful humour and lyrical yearnings. And there's celebration all the way - not so much a case of vive la difference as vivent les differences.
David Hill is a Taranaki writer.