My initial impression of this -- that is, the impression as I read it -- was not favorable. Its main character was one-dimensional. The plot turns could be seen coming pages in advance. It had improbable coincidences (happening to be at Harvard the day he was awarded his degree). It seemed odd that it addressed much of the adult life of Nat Bowditch rather than just his youth (after all, Harry Potter's adult life is summarized in a few-page epilogue).
Yet after I read it, it grew on me. It was a classic by-the-bootstraps tale. It had adventure, history and, pleasantly, science. In hindsight, I was glad to have read it.
Then, THEN, (only today!) I learned that Nat Bowditch was not a fictional character. This was a fictionalization of a real person. Mr. Bowditch really did get indentured, develop a new way of calculating lunars and create a sailing manual that is still a classic.
I wish I had known this going in. The book's sense of inevitability would have been much easier to understand.
I don't expect either of my sons would enjoy this book, now or ever. But I am glad to have read it.