If you enjoy firearms, and if you enjoy more hitting the target at various distances, you need to know how much the bullet drops as it travels. You need to know how much the bullet you fired drops at different distances so you can correct your scope or compensate for the drop by aiming higher. All you have to do is look the data up (in the book) by caliber, brand, etc. and presto! now you know how much you need to adjust your scope, or how much higher to aim.

Another good thing about this book is all the time it saves me. Without this data I would have to find me a long range, and fire a bunch of shots to figure out this data on my own.

I get these books the minute they come out each time. Nice to have a source of up-to-date information at my finger tips. But, just realize that it takes months to get a book to print and to retail. In that time there have been new products introduced and changes that are not reflected in the book. But I still highly recommend the book as a great reference source. You can always follow up with internet searches.