This book is written as two parts. The first is an overview of the current state of research into the causes of autism, in turn divided into subsections on brain structure and genetics. The second is a personal and impassioned but not terribly coherent plea for Aspies to be defined as much for their strengths as their weaknesses, indeed for Aspie traits to be seen just as traits without any attendant value judgements about them at all.
Part 1 is excellent, giving a very comprehensive picture of what is and is not known about variations in brain structure between neurotypical and autistic brains whilst providing necessary caveats about the limitations of the imaging equipment used (especially fMRI which I advise all readers to be extremely sceptical about when used in psychological experiments). The follow-up on genetics is just as good, revealing that there are hundreds of genetic variations implicated in autism and that many of them are associated with the brain in some way.
There is a also a short discussion of environmental factors (drugs, pesticides etc.). It's short mainly because there's been very little research on the subject.
If I am to be critical of part 1 at all it is that some of the technicalities of both brain anatomy and genetic theory aren't explained in sufficient detail for non-biologists. (My lack of grasp of genetics is an increasing frustration to me; if you know of a good introductory text on the subject please tell me about it!)
Part 2 is not so fabulous and causes a star to be docked. The material is much more personal and is not organised in a very clear fashion. Grandin admits that this has never been her strong suit but her journalist co-author was evidently unable to completely sort out the problem.
There seem to be two main points. The first is advocating research that is based on single symptoms. Instead of taking autistic people and comparing them to neurotypical people, take people with a specific symptom, e.g. extreme hearing sensitivities and compare them with people who don't. One does not necessarily have to be autistic to have such a sensitivity and if you're autistic you won't necessarily have it either. This makes a great deal of sense to me from a scientific stand-point and I hope researchers adopt the approach.
The second main point is to try to see past labels to people and recognise their strengths as well as their weaknesses and that traits are actually neutral and are only strengths or weaknesses in their contexts. Well, I can get behind that but along the way we are treated to some bizarrely self-contradictory opinions.
On the one hand we are told that Grandin was hopeless at geometry and that her teacher should have given up on the subject and taught something else she could do instead e.g. algebra. On the other, we are later subjected to a rant in which Aspies with various difficulties that Grandin doesn't have should essentially "get over it." I find this to be on exactly the same level as telling a depressed person to "pull yourself together" and pretty offensive.
Taking this along with her completely false (and now dropped) assumption that because she is Aspie and she thinks in pictures primarily, all Aspies must think in pictures, what I see is a woman who is very poor at figuring out the level of variation there is in human modes of thought. Assuming everybody sees the world the way you do is, however a very Aspie trait!