I read this book really fast. It was that interesting and easy to read! Or even, fascinating. Lots of scientific concepts building up in a nice good progression, joined with great complementary historical background that completes the "bigger picture".
It also reminded me of many "popular science" magazines back in the 80s and 90s—I felt like all these magazines were doing was just rephrasing Carl Sagan's book, but doing a poor job at transmitting the actual ideas. I finally understood many of the concepts they dabbled with by reading the book, but not back then (admittedly, I was also a lot younger, so that might have had something to do too, but still...!)
It's also a great book if you like science fiction books as it explains many concepts that are then utilised in the books. For example, how space ships can use the gravity of a planet to propel themselves into further distances.
It makes you think and reconsider many things, but probably the ones that impacted me the most were... One: how small and miraculous we are and how great it is that we exist. Two: how miraculous it is that we've launched stuff into space and those devices haven't crashed, AND they keep working so many years later—it's such a monumental scientific achievement!
It's not perfect though; it shows its age. It is incredibly concerned about the nuclear menace, and the Cold War, and the URSS bombing the USA bombing the URSS and eventually killing everyone in the planet. Which is understandable for the time the book was written—but it seems that the biggest menace is in fact a combination of exacerbated capitalism combined with global warming. But could Sagan have predicted this? It'd be interesting to find about his thoughts about 10 years later after the book was written, to see if he had changed his mind.
Overall, a very inspiring book that leaves you with lots of pointers to things to check and learn more about. And it also leaves you sad that Sagan is not with us anymore :-(