Eli Bendersky's website I first borrowed this book from the library a few years ago when I took an "evolution" course in Uni. I liked it so much that I decided it's a "must have", so I bought it and read it again.
"The selfish gene" is a compulsory book for any scientifically inclined person, I think. Dawkins' ratification and expansion of Darwinism is priceless, an amazing example of rigid scientific thinking. His lucid writing style, and especially his unyielding drive to stick to facts and science, opposed to other approaches that rely on faith (which by definition means believing in things one can't prove) is inspiring.
Other than serving as a brilliant primer on the modern understanding of biology and the origin of living species, this book also has powerful philosophical deductions. Reading between the lines, I think that one can shape concrete answers to some of the most profound questions that face humanity, such as "why we are here", "what is the meaning of life", etc.
As you can see, I can hardly be more enthusiastic about this book. It's true, I think it's a masterpiece and one of the most important books everyone should read. If you still haven't read it, do it, you owe it to yourself.