Strong images, but all too scrappy

This is my first novel Sam Millar, Northern Irish in tumultuous past converted into writing.
It definitely has a nice pen, humor and talent to highlight the tension shock scenes. The first chapters of the novel are very strong.
The book has the merit of not too spread out, the chapters are quite short, the novel itself being only 250 pages.

I did not like the rambling building of the book, the plot too classical, the ubiquitous and sometimes cartoonish sadism. Above all, the main character does not really appealed to me, I did not feel a lot of empathy for him.
The final twists are a bit disappointing, a little too easy to guess.
This is a detail but the choice to epigraphs to each of the thirty-five chapters (plus prologue and the epilogue to one) is quite painful, even laughable. There is no point. As one of my former professors, culture is like jam: the less you have, the more you spread.

Overall, it's pretty nice to read, sometimes funny, but I struggled to get involved in this reading beyond the first chapters.