This is a collection of little vignettes about progressive and radical thinkers--many, many of them in one volume. Each person gets one short essay exposition, explaining life, ideals, and accomplishments. I believe the purpose of the book is to inspire readers with the great variety of approaches to progressivism/radicalism, and to an extent it certainly does so.
I read the bulk of this book in two weeks a few summers ago, and I just couldn't get through it. I finally returned at some point and read the last few sections. I confess I had to force through it at times--one of those books you feel more obligated to get through rather than riveted by... It's a little too much in a little too small a space. There is absolutely no flow to it; it's maybe better read here and there, or by picking out essays/thinkers in whom you're particularly interested.
I dunno. If you are an aspiring progressive, you might like it. When I read it, I aspired to be an aspiring progressive, and for whatever reason, it let me down.