I mean, it's the book that made me a geologist, so obviously it left an incredible impression on me. I love the in-depth descriptions of historical eruptions and particularly the chapters on the regional geology of each island and volcano. It's the storytelling that sold me on geology, I guess. I really love chemistry... REALLY love chemistry... and so once in the geosciences I gravitated to mineralogy, petrology, and geochemistry, but I wanted those stories to be the structure of why I studied and worked on what I did.
The first edition was written just as plate tectonics was getting settled, primarily by an elder statesman who had done his core work prior to that time, and a lot of that survived into the second edition. Pu'u O'o had just gotten started when the second edition came out, and of course there's been a metric shit ton of other work since then as well. This book badly needs either a third edition or someone to write a new book to address the same themes. If that has already been done, leave a comment with the title / author / isbn...