I am defending my PhD thesis on black holes this spring. I bought this book for many of my relatives this holiday season.
For the science-loving, non-expert reader, this book is an excellent, intelligent and extremely up-to-date introduction to astrophysical black holes. The authors have done a phenomenal job of explaining the current scientific understanding of black holes, with hardly any math at all.
The book is filled to the brim with the cutting-edge hypotheses and observational evidence. The lucid explanations are accompanied by numerous colorful and informative illustrations and figures. Many of the pictures are adapted or taken directly from the most influential academic articles of the last 10 years. The authors also give brief sketches of the people behind the science, from Albert Einstein (whom everybody knows) to current leaders in the field such as Roger Blandford, Reinhard Genzel and Andrea Ghez (of whose work and names every astrophysicist --- but almost no one else --- knows).
I would also recommend this book to any interested college student or advanced high school student, as well as to interested teachers. I've taught physics and astronomy to students at those levels and given public lectures on black holes, and am always thinking about how to talk to non-experts about black holes. I've encountered few teachers and professors who could explain the subject better than Drs. Begelman and Rees have done in this book.
For any undergraduate or beginning graduate student considering doing astronomy or astrophysics for a living, I can't think of a more comprehensive or accessible overview of black holes.