I gave this 4 stars as I feel she could go further here but it is a good start, anyway.
Now, the previous reviewer sounds like someone threatened from the pharmaceutical community. (oh goodness, can you imagine how much money they would lose when more figure out this is all diet related and no drugs are required?) It's obvious, too, that the previous reviewer lacks ANY degree of context or understanding what life is like with a child reacting/acting out a wide range of behaviors and health concerns.
So, moving on to the book. Sue's book is very good. She goes in to detail about various types of foods that can cause reactions.
My one complaint is she trashes Feingold. Frankly, we do the Feingold diet and have had great success. Sue says that Feingold doesn't go in to detail. (She obviously never ordered the materials as the binder educates what to do when the first level of the diet isn't enough.)
So, if you're in Australia, I DO recommend her and the link to the hospital department that has safe food lists.
If you're in the US, order the Feingold materials (feingold.org OR ADHDdiet.com) - it's tax deductible as Feingold is a non-profit organization. The foodlist is worth its weight in gold. There's a sister organization in the UK, sorry - can't remember it's name at moment.
Lastly, Sue doesn't explore what can be a major key for many families who need to go this route: use of Enzymes.
There's a forum over at Yahoogroups called EnzymesAndAustism that has nearly 3,000 members and frank discussions about enzymes, which company(s) [I'll not mention the company here as I don't want to appear that I work for them - I don't, of course but believe in them!!!] and also other potential (non-medical) treatments. Btw, the group is not just for autism... a whole HOST of behaviors includding ADHD, ODD, PDD, ACD, AS, Asperger and so many more are discussed there. Plus, enzyme help for those who are also GFCF. http://health.groups.yahoo.com/group/EnzymesandAutism/ Visit the group's homepage to see the description in order to discern if lurking in the group will be beneficial for you.
Bottom line - Yes, the book is worth the read, and depending on your locale, a really book jumping off point.
Keep in mind, though, that this book is not the last word on the subject. Always do your own research to discern what's right for you and what works. Good luck!!!