"Be patient; it will pay off"
The detail is tedious. Everyone is so terribly sensitive, and trivial interactions take pages. But every few pages there is a "ping," of something not right, or a growing realization that there are large things missing in this detritus of kids at a boarding school fussing about their feelings. Then you slowly realize what is missing, and some of the trivial events reappear with deeper meaning. Two-thirds of the way through you realize the importance of the author's emphasis upon tedious little spats and hurts and crushes, and then the reader (who is fine) annoys you because she can't read fast enough as the horror mounts and the jigsaw gets completed. It is not science fiction at all, as some say; it is all at hand and little prevents society from seeking this path to health.
"Irratating hero, mumbling sidekick"
Not likely. Hero was full of cant and self-absorption, homilies pouring out about how smart or good he was, overladen with a quite conservative social point of view. The most interesting and well portrayed character was his crazy daughter; she sprang to life when entering the scene.
Remarkably, there was no "ending." The fanciful murders and holes in the walls were never really explained, frustrating a long wait for a resolution
The partner assigned to the hero was given a more heavy Irish accent that often drifted into a mumble and I had to guess at what was being said, even after replaying
"Gratuitous violence"
After only 2 hours of listening we get a rape, a long series of Gulag torture scenes, two instances of naked children disemboweled and otherwise graphically cut up, and other violent scenes. The depiction of life under Stalin was quite interesting, but the prospect of more violence from a serial killer and the state security apparatus was not worth it. I quit.
"Gave up"
This is no Copenhagen, the brillant play by Frayn. The two boys are impossibly, endlessly and tediously credulous, while one of them, the narrator, is at the same time unbelievably perceptive about the little village (wonderfully depicted -- but the book needs more than that) and its humdrum people. Not much seemed to be happening half way through, though one see where it is all leading, and no children's imagination could be that overheated. The reader, however, kept me going that far; he is wonderful. But I still gave up.