Wow, where to start with this one? It's a bit confused but very thorough.
The main problem i have with it is the order, there are three separate introductions, relating to three different editions of the book, and then the sections aren't totally in chronological order, although it makes sense based on how the talks with Mary were done.
Once i accepted that, it was a really absorbing read. It's uncomfortable subject matter, but i had to keep reading.
This was written in the late 90's, while the crimes themselves took place in 1968, so you have to keep in mind that the general attitude to children in 1968 was closer to that in the time was written (and so even more shocking for a modern audience) and also when the author links these events to more recent crimes, a lot has happened and changed even since then. However it is sad to realise that, even with the progress made there is still a long way to go, and as the author points out, the situation in America doesn't seem to have changed much either