Eli Bendersky's website In this book Sagan returns to the cosmic theme, about where he left off in "Cosmos", telling interesting facts and research results about various planets in our solar system. Here, however, his emphasis is on the human aspect of space exploration.
Thus, the book is full of fascinating information about various space exploration missions launched by humans (mostly US and the former Soviet Union), the outcomes of these missions and the lessons we learn from them. Told in Sagan's unmistakable narrative style, most of this book is a pleasure to read. Not less engaging are his speculations about our future in space. Sagan doesn't stop at abstract conjectures, he gives some hard numbers on how humans can settle Mars, a few of Jovian / Saturnian moons and even several asteroids. He claims that the technological capability for an initial settling of Mars, for instance, already exists. What is lacking is money and funding.
And this brings me to the issues I have with this book. Sagan gets too much into polemics. I raised this topic with the previous book of his I read - "The demon haunted world", and it's probably even more detectable here. It seems that in his later books Sagan fails to keep his personal opinions out of the text. In "A pale blue dot" he spends tiringly long sections bitching about the incorrect (in his, not so humble, opinion) decisions the US goverment made in funding. Cancelling various space missions / endeavors, not giving enough funding to others. He keeps comparing how tiny NASA's budget is compared to the defense budget. Now, don't get me wrong, it's not that I don't agree with him (in fact I don't know enough to have an opinion), I just feel that a popular science book is improper for such content.
Anyway, the book is generally good and I liked it. If you whizz through the polemics, the content is very interesting. I sure learned a lot about our solar system and about the space missions launched by humanity before year 2000.