This book contains a lot of good information on submarines in general, not just those of the U.S. Navy. Basically, I more or less agree with all of the other reviews regarding the value of the information Clancy provides, which is quite good and a genuine pleasure to read. Obviously, a lot of the information is classified, so about half of the book is Tom Clancy's best guesses, which are definitely more educated than mine. However, I sometimes find his writing syle rediculously all-knowing and jingoistic. I guess you have to take the good with the bad; the good being the abundance of research, as well as the overly conversational tone in which it is presented, and the bad being all the drivel you have to swim through to get it. Still, I don't think there have been very many people who have done as much for the military in terms of giving credit and honors to the people who serve than Tom Clancy.