Her new book is The Death and Life of the Great American School System: How Testing and Choice are Undermining Education. Her bottom line is this:
The more uneasy I grew with the agenda of choice and accountability, the more I realized that I am too "conservative" to embrace an agenda whose end result is entirely speculative and uncertain. The effort to upend American public education and replace it with something market-based began to feel too radical for me. I concluded that I could not countenance any reforms that might have the effect — intended or unintended — of undermining public education.
Ravitch of course was once the number one advocate of these very ideas; read this excellent article on her intellectual evolution.
Overall it is a serious book worth reading and it has some good arguments to establish the view — as I interpret it — that both vouchers and school accountability are overrated ideas by their proponents. (Short of turning the world upside down, some school districts will only get so good; conversely many public schools around the world are excellent.) But are they bad ideas outright? Ravitch doesn't do much to contest the quantitative evidence in their favor. There are many studies on vouchers, some surveyed here. Charter schools also seem like a good idea.
Is American public education such a huge success these days that it should be immune from significant restructuring? I don't think so. One of the best arguments for our current system is simply that — because it is lax — it doesn't waste too much time for the really smart kids who want to be doing other things. That's an important factor but hardly a ringing endorsement for the system as a whole.