"Red Sister" is a high impact book that has some powerful scenes and some novel ideas but which is weakened by a clumsy structure and very limited character development.
It starts well:
"It is important, when killing a nun, to ensure that you bring an army of sufficient size. For Sister Thorn of the Sweet Mercy Convent, Lano Tacsis brought two hundred men."
It's packed with well described violence and dramatic confrontations. It has an all-female school for assassins (imagine Hogwarts where everyone was in Slytherine and the favourite class was Offensive Use of the Dark Arts), new magic tropes, an ancient pan-galactic civilization to catch up on, a brutal, corrupt, theocracy and the rough equivalent of cage fighting, only with child combatants.
What's not to like?
Well perhaps the enslavement and abuse of children through out the book and the glamorisation of pointless violence on an enormous scale.
Reading "Red Sister" was like watching a Tarantino movie, (not the ones with the clever scripts, more like "Dawn til Dusk") only without the humour, You find yourself spellbound by the action and repulsed by the people.
The thing that I liked least about the book was the clumsy structure for imposing a "here and now" timeline over the main "backstory" that the novel focuses on. It seemed forced, gave a sense of foreboding that it couldn't live up to, and served no purpose except to set up the next book in the series.
The audiobook version is more than nineteen hours long. It kept my attention all the way through and had me going "wow" every few chapters. This is above average fiction... in parts. Enough parts for me to say, "I loved the scene where..." but not enough to say that I loved the book.