First things first: I'm biased. I've met Sister Rosemary and knew the basics of her story; she's an incredible woman, and I don't think there's anything you could say to make me change my mind on that score.
Second: The book. I don't see the point in rating a book based on the subject—it's what you do with that subject, that story, that makes it or breaks it. Now, Whitten is biased too. He's involved in St. Monica's (mostly fundraising-end stuff); the proceeds from this book go to the nonprofit he started. This was never going to be an in-depth, hard-hitting work of journalism. If there are any 'off' characters, we aren't going to hear about them here.
Still...the basic read was enjoyable. My knowledge of St. Monica's and Sister Rosemary's work was rudimentary, so this painted a much fuller picture for me, which I appreciated. More history might have been helpful—this wasn't, I know, the place for an in-depth look at the LRA and the destruction they wrought, but I would have loved to see more of the students' stories woven into the text. Two or three of them, for example, told sort of in parallel with Sister Rosemary's story (as more than just anecdotes)? I'm not sure. In some ways their stories are the heart of Sister Rosemary's, and I would have liked to see more.
Less interesting is the Pros for Africa end of things. At one point it felt like it was just a list of famous people/athletes who had gotten involved, and that part of the story occasionally dipped into, for a lack of a better term, uncomfortable-overtone-sentimentality: Scooping cups of beans, rice and flour from plastic buckets into the grateful villager' tattered bags, they were touched by the sight of old ladies bending over to retrieve each precious piece that fell to the ground (178). The story's stronger when it sticks to Sister Rosemary and her work (does it tip over into sentimentality there too? Yes. But less uncomfortably). Nice to hear about some of the little things, too—Even after graduation, a girl was welcome to bring her children back to the daycare center every day for three or four years, free of charge, while she worked to secure a solid future for her family (152). Or rather, I suppose that's not a little thing (three or four years!), but what a striking example of a solid understanding of how hard it can be for a single mother, one perhaps with a history of trauma, to get her feet beneath her.
Do I recommend the book? Yes and no. As a book...not really. Inspirational story, if you're into that sort of thing, but the execution is decidedly meh. But—can I recommend Sister Rosemary, in general? (I told you I was biased.) On those grounds it's more worth the read.