I'm about half-way through the book and I'm happy to say that, yes, it improves. The first chapter is abysmal, with stilted dialogue and some clunky symbolism (the writer burns his hand on a cast-iron pot, is unable to write, falls down the stairs into a dark basement, blah blah blah), but it picks up from there.
The titular character is facing a dilemma at 70: does he continue to mourn his wife, who's been dead for a decade, or does he make a marriage proposal to the younger woman he's currently with (who happens to have been his late wife's colleague)?
And more crucially, is it even possible to love someone ever again, if the person you happened to lose was in many ways your "soulmate"? A profound question, the more I think about it.
I do hope that Auster handles it well, I will report back after I finish the book. His recent battle with mortality, as well as the loss of his child and grandchild in quick succession, might have done something to his vision, might have darkened (but also deepened) it in unexpected ways.