>Nothing persuaded me that he had anything interesting to add - neither rationally, nor aesthetically - about a topic which has been covered by philosophers throughout the millennia.
That sounds more like an emotionally charge reaction than some calm assessment on the merits of the book for what it stands.
Especially when the idea here is that he presents his idiosyncratic vision of the concept of “truth" - not some claim that he solves the problem of truth "which has been covered by philosophers throughout the millennia", and which could very well be inherently unsolvable anyway.
A writer (even more so, an artist with a unique viewpoints) can add lots of very interesting observations and new ways of seeing the concept of truth or our approaches to it, even when they do it "in the small", without taking on or pretending to tackling the philosophical / ontological core issue.
It's even more useful if an author says some things that rub you off the wrong way, or challenge your core tenets. Else, I guess one cal always just resort to some echo bubble friendly comfort reading.