From early on Red Rising reminded me of Dune by Frank Herbert. Power struggle in space centered on a young man. In Red Rising this young man, Darrow, just happens to be of low descent, unlike the high-born Paul Atreides. Later, the story began to be more reminiscent of certain YA dystopians, but I still suspect Pierce Brown has read his Dune.
The story kicks off strongly. The early events create tension and maintain interest excellently. Darrow seems to be a sympathetic guy. But then the schoolyard brawl begins, in which parents, teachers and other people try to get involved to the best of their ability. I never got interested in these kind of quarrels when I was a kid, and it wasn't much more engrossing, even though it occurred on Mars. In addition, Darrow became more or less monstrous as the hassle progressed.
I would say that the first part of the novel was whopping great. All the other parts were rather much more painful reading, but the very cliffhanger ending led me to believe that the sequel could very well raise the level of interest again.