This is probably a minor novel by Grass, but still it's often breathtaking.
I particularly liked the work of historic research that made the basement of the novel. Unless the tragedies of Titanic and Lusitania, quite a few people knew about the shipwreck of the Wilhelm Gustloff.
The scene of the sunken ship built with Lego bricks is unforgettable.
Moreover it's praiseworthy (albeit not always convincing) the way an estimated author in his eighties, like Grass is, tried to put the part played by the internet in the frame of this novel.
There is also an interesting analysis about German press and media nowadays with very strong words against Springer I still recall.
A few years before his astonishing "auto da fe" about having once been a Nazi supporter, Grass wrote about the dangerous rise of well-taught (yet sectarian-taught) Neonazis in contemporary Germany.
While re-read today I'm sure this book would have something more to tell.