This book is dense in places and, in my opinion, isn't a good introductory book on the subject of evolution (and, perhaps, isn't meant to be). If I had to choose between this or another text to initiate someone, I would probably pick Jerry Coyne's Why Evolution Is True over this text (likewise from 2009 and referenced by Dawkins in this work). If I had to compare any two books by biologists on evolution, I think Coyne's makes a better case and is more general where it needs to be. That said, as a supplementary reading on evolution, The Greatest Show on Earth is worth a read.

I don't think many people could deny that Dawkins is a knowledgeable biologist with some rhetorical flare.