I fully agree with Hitchens' assessment of Gunter Grass, in Slate, here:
For all this, one was never able to suppress the slight feeling that the author of The Tin Drum was something of a bigmouth and a fraud, and also something of a hypocrite. He was one of those whom Gore Vidal might have had in mind when he referred to the high horse, always tethered conveniently nearby, which the writer/rider could mount at any moment. Seldom did Grass miss a chance to be lofty and morally stern. But between the pony and the horse, between the stirrup and the ground, there stood (and stands) a calculating opportunist.
Still, and while saying that his writing has been the screed of a hectoring bore for decades and decades and decades, Grass is nonetheless the author of The Tin Drum. Grass had one masterpiece in him, and that is it.
(The film, in its own way, is also a masterpiece. A couple of years after it was released in 1979 or thereabouts, I had the opportunity at UCLA to take a class with an aged, aged theatre professor there, whose name escapes me, but who had premiered a couple of Brecht's plays in Vienna before they both fled the Nazis for southern California. This professor stayed on after Brecht saw, in his consumately cunning and self-serving way, the opportunity for a state theatre in East Germany, a West German passport, and a Swiss bank account. Anyway, said professor remarked that the film version of The Tin Drum was the last great gasp of German expressionism, a voice from the Weimar past suddenly breaking out in the 1970s. He would have known whereof he spoke. What was his name?)