No good at all. Other reviewers have already pointed out that the hero is unlikeable, the plot lacks both tension and resolution, and the language is anachronistic. To make his hero seem really gifted, the author resorts to a simple expedient of making the others act in a dangerously obtuse way, and we are expected to swallow it without a question.
But to crown it all, the author just can't write, or at least does not believe in editing his text once written. This book has sentences like "It was hard to see
how the men could even see
what they were doing..." and "Obviously
Purnell had money; he was very well turned out and was obviously
someone's favorite to be there..." The battle descriptions actually have exclamation marks on the end of half the sentences! As if a schoolgirl were caught up in it and decided to describe some in a letter home. Lambdin's prose is inexcusable.