It is really an introduction to the consequences of Darwinian evolutionary biology in the modern world. But to get there the first 1/3 is a rather nice simple biographical sketch of Darwin and his times. One particularly good accent was on the Platonic essentialism that marked much of the historical thinking about biology up to Darwin's time. As such this part of the book would be a good first read for a high school student on Darwin.

The second half is his desire to convince people that Darwinian thinking is crucial for a good understanding of not just the natural biological world but for greater issues like sociobio to medicine. As such is a good general survey of an extremely polarized subject material without getting bogged down in the debate itself.