I reviewed this a while ago on another site and lost the review, but what I remember about it is a solid good. The title is misleading, because the book focuses primarily on the White Rose and not Sophie Scholl herself. I've read other books on The White Rose so was looking for something a little more personal about Sophie so in that respect this book was a disappointment.
What never fails to disappoint and amaze me about The White Rose and Scholl in particular is her tremendous courage. What I can't tell you is whether this book or the movie based on it had more of an impact; I think I'd have to confess to liking the movie better than the book - the sense of urgency is greater in the film and visuals help the setting more than the book does.
Nevertheless, it's definitely worth a read, particularly to leftist and liberal activists of many stripes. If it does nothing else, this book will inspire you even as it scares the hell out of you.