At times laugh-out-loud funny, consistently illuminating, delightful to read from start to finish. I learned a ton, and actually plan to re-read this at times to refresh my understanding of a number of concepts that Katie lays out. As a lay-person with a fair degree of interest in (but no training in) astrophysics, this book was a perfect blend of insight, explanation, and break-your-brain theory. Cannot recommend this highly enough.