I'm a fan of Yang's, and I've been looking forward to this title and the companion book, Boxers. At the same time, I had no prior knowledge of the Boxer Rebellion. Saints is intense, deep, moving, and it motivated me to read more about the rebellion. In the back matter, Yang provides a list of titles for further reading. 
 Saints depicts parts of the Boxer Rebellion through the eyes of Four-Girl, from age 8 until she turns 15. We learn about her family life, and watch the story unfold as she becomes one of the enemies of the Boxers, a Chinese Christian. 
 The artwork, as ever, is perfect. Once in a while I found the layout of the panels confusing, and I needed to backtrack to determine what was happening. When this occurred, it felt like small bits of the story had been skipped, and that's one of the reasons I didn't give a higher rating. 
 If you have interest in reading this, I suggest you also read Boxers. The two are meant to go together, though I believe reading Boxers first will provide more background and information, and give you some solid call-back moments during your reading of Saints. 
 Edit--My 12 year-old son also read both Boxers and Saints, after a warning from me about how violent they are. He's sensitive to that, yet a huge graphic novel fan, so he finished them. He says he would give them both 3.5 stars because they "are just too violent for my tastes, even though the violence is based on history." These aren't books for kids, though my sensitive boy did fine. Use your own best judgment.