It's unsure of why Kennedy put this in place. He was planning a memoir and possibly hoped that he could review the recordings to help his writing. It's also very plausible that he installed the devices due to the bad advice he received during the Bay of Pigs debacle. The recordings would provide evidence of who suggested what and when.
The recordings included in this book are extremely entertaining and enlightening. Recordings documenting phone calls between the President and former Presidents Eisenhower, Truman, and Hoover are great. The recordings allow us to eavesdrop on the Cuban Missile Crisis meetings as well as the Civil Rights meetings. We get to hear a few self dictations Kennedy would record alone at his desk concerning some of the things he was dealing with and thinking about. A few of the recordings have excerpts from his children as they would routinely barge in his office even during serious diplomatic meetings.
The result of these recordings is an even deeper understanding of JFK and an inside look at the pressures and convictions of the President. Conversations between he and his brother were entertaining for sure. It was great to read and later listen to the way they would finish one another's sentences and the way they playfully joked and cut up. This book came with 2 hours worth of recordings straight from the book allowing the reader to follow along between the book and the CD.
I'd say this was some of the best money I've spent on a book. This is a must for any Kennedy fans, but also enjoyable for fans of the presidency and history. At 286 pages, it's a very quick and easy read.