I don't agree with the hype that this book is "easily read and understood by the layman". I think one needs a basic biological background to understand it. This is a good book if, like me, you had a cursory and very dry introduction to embryology in the past, and wish to fill in the gaps. If you don't have some basic scientific knowledge, forget it.
The writing style, in British English, is at times awkward and clumsy, with attempts at humor that seem rather precious to American ears. Certain key words like 'homeobox' are also casually tossed around several chapters before they are actually defined. The writing level varies rather widely, at graduate biology level in some places while in other areas the discussion was quite simplistic - far too much so, with important points in late emybryonic development, cancer development, and genetic mutation being glossed over or completely left out.
I think the concept of writing a readable embryology text is a good one, and this was a brave attempt - it's certainly better than most of the available dry textbooks on the subject. However, this book struck me as trying too hard to satisfy both the layman and the scientist, and comes up short for both audiences - half of one and six dozen of the other, so to speak.
I would love to see this book expanded to include more detail on the stuff people really want to know - what about human genetic issues and mutations? What about cancer genes? The book also needs a style overhaul to speak at the same level throughout. That being said, it is a mostly an enjoyable book, if embryology is something you like.