File this one under "things you knew, but didn't really know before." Most of what's in this book didn't surprise me, but Alexander's thorough documentation of the mass incarceration of African American men, particularly, as a result of the drug war gave me a fuller appreciation of the dimensions of the problem. It makes a good sequel to Douglas Blackmon's Slavery by Another Name, which I read last year.
Here's one thing that did surprise me: as recently as the 1970s, "the notion that our society would be much better off without prisons--and that the end of prisons was more or less inevitable--not only dominated mainstream academic discourse in the field of criminology but also inspired a national campaign by reformers demanding a moratorium on prison construction." We almost dodged this bullet.
Alexander's final chapter gives a sense of just how difficult this situation will be to change (prisons are big business now). I think she's right that a mass movement is necessary, because this change will have to be radical, not incremental; I hope we're seeing the beginning of that movement. But there sure is a long way to go.