A Nothing Named Silas, by Steve Westover.
(I read this one last year, but am just now getting to the review . . .)
I thought the book started really promisingly. Silas has trained his whole life to be accepted into one of the elite units (Command), only to have a chance accident result in his being drafted into the lowest of the units: Labor. Once there, Silas finds himself repeatedly humiliated and abused by Taelori, the Labor Regent. But once he passes her seemingly arbitrary tests, he's welcomed into the group. However, things aren't entirely what they seem (of course!): Silas stumbles across a group of rebels who want to change the system of government and invite Silas to join them. Between the growing number of secrets he's learning to keep and a girl he's coming to admire, Silas finds life quite complicated: who should he trust? The Regent who has abused him, or the revolutionaries who might not be telling the whole truth.
The story as a whole moves pretty quickly. For a dystopian world, this felt new, like something I hadn't seen before. However, once Silas became established in Labor, I had a hard time relating to Silas, whose sympathies seemed attached to a pendulum and changed frequently, depending on what he'd just been told. I wanted Silas to trust his own judgment a little more. I also felt a little underwhelmed by the big secret--I know some readers/reviewers loved the climax reveal, but it didn't quite work for me.