Spoilers: Both the novel and film take place at a small WASPy college in Ohio during the Korean War. The protagonist is a smart-alecky nice Jewish boy from Newark. He becomes involved with a sexy, psychotic blonde-haired, blue-eyed Christian girl. He makes some bad alliances, some bad choices, and in the end he dies a virgin -- well, maybe not, it depends on your definition of sex -- in Korea.
There's one fantastic extended scene between the hero, played by Logan Lerman, and the dean, played by Tracy Letts, in which almost all the dialogue, according to Schamus, was lifted from the book. It's an elliptical debate in which you hear the dance of language and you can sense the joy in the actors as they chew on each piece of dialogue, as they talk around issues of sex and the claims to territory between dominant and non-dominant groups. You don't see enough of this kind of thing in mainstream American cinema outside of Tarantino movies.
But the rest of the movie is boring and bloodless. Adaptations are not about realizing an ur-text in a new medium. They are about using a source text to describe something new. Still, there's so much more Schamus could have lifted from Roth. I don't expect him to adapt the long description from the novel about the workings of a kosher butcher shop, although, now that I think of it, a long 15-minute mini-documentary about life in a kosher butcher shop stuck right in the middle of a movie like this would have been wonderful. I do expect him to try to realize some of Roth's sexual madness. No self-respecting gay man, or human being in general, liked the sex scene in the Schamus-written Brokeback Mountain. You didn't believe for one second that Jake Gyllenhaal was taking anything from Heath Ledger. Where were the bodily fluids? What exactly was at stake? Indignation has the lamest blow job and lamest hand job I have ever seen on the screen. Roth can't help but describe cum in his prose. You need to go broad to make these scenes work. I needed something like Vince Vaughan's near-ejaculation face from Wedding Crashers or the masturbation scene at the end of Happiness. I needed to see some cum on the screen, dripping off a lip or soiling a hand.
Roth's heroes die because they need to cum. You need to show that cum on the screen. Without it, you just can't get the comedy, nor the tragedy.