Diary of a Bad Year is an exceptionally moving investigation of what it means to have singular opinions in a plural universe. The short, diverse essays at the top of each page signal a diminishment of writerly power. They might evoke a hollow echo if published alone. At least one reviewer sees this as a problem to the success of the book. Yet if they were more fully-developed, they would crust over what is currently an open wound. And it is the gaping wound with which Coetzee's is concerned. Success, in this sense, would be failure.
I think Steve is pretty near spot-on with this, but I don't agree completely. I think there was a tiredness to the novel, beyond JC's tiredness; a frustration with the novel form, beyond the frustration discussed in the essays; a perfunctory quality to some of the writing, beyond the artful intent to leave the work "open": success would, indeed, be failure here, were the work to be too complete, but I still think Coetzee could have failed better.