Not Dawkins' best book. It is a transition, when Dawkins was first awarded the professorship for the public understanding of science. Not yet a rabid atheist (very entertaining) and not quite the neodarwinist. Dawkins strays into areas he is not fully conversant with, while trying to balance the justification of the scientific method and the poetry of symbolism. I think this results in some awkwardness in the narrative and at times he gets stuck in a subject, straying into refuting the symbolism of other evolutionists with which he disagrees.
Still the revelations about the Y chromosomes in birds and the particular consequence with reference to the cuckoo are both fascinating and enlightening. How can one doubt the power of the gene when presented with an animal which changes its egg design depending on the ancestral mother? Completely compelling.