I came to this series "in the middle", starting with this book without having read the first four. But, having considerable exposure to WW II history I figured I could step into it without getting lost. That's true in the sense that I knew about Pearl Harbor and Guadalcanal, but the characters were almost all new -- a few were actual historical figures that I had some idea of, but it's not the same as having read the previous books. Likewise, I had some familiarity with WW II submarines, having read LCDR Grider's memoir and "Run Silent, Run Deep," probably the best submarine novel of WW II. I was impressed by the author's obvious familiarity with the operation of submarines of the period, as well as his mastery of the regional dialects of American English -- he has the New England lingo in particular nailed. (My sister, after 20 years in New Hampshire, remarked that "because she lacked a grandparent who was born there, she was still 'from away,' a transient.")
The story is fast paced and authentically taut, with a near impossible mission: sail up to the big Japanese base at Truk and attack a battleship. Both plot and characters are well developed and entertaining. The idea of basing each chapter on the crew's letters home, under a promise from management that there would be no censorship on this voyage, is a little odd and takes some believing, but it does give a framework for the action that is innovative compared to most WW II fiction. I'm not sure it's entirely successful, as it does inevitably slow down the action, but of course, the reality is that the war was "hours of boredom interspersed with minutes of terror." So, bottom line is I thought this book was a worthwhile read and a contribution to the still-growing literature on World War II.