The novel holds to the facts of Jackson's life about as well as the movie Gods and Generals does, that is to say, fairly accurately. Thoughts and conversations are, of course, invented, and this is where the novel is weakest. As is often the case with 'spiritual' novels that relay religious thoughts through the main character's thoughts, The Other Side of the River often comes up as cheesy and contrived. It is not my favorite way to embed faith into a book. Because there is a concrete story to follow, the book does not exist for the sole purpose of preaching — it's not as overtly spiritual as other books I've come across.
The writing is questionably good. This novel doesn't have the striking prose of, say, Gods and Generals or Last Full Measure, or any of Shaara's war novels. The battle scenes will not grip you as you turn pages. So, sure, the writing's good, but for a war novel, there isn't enough passion. And perhaps that reflects the focus of this novel: it isn't a page-turning thriller. Instead, it's a more personal look at Jackson himself.
This could have made The Other Side of the River a real winner, if it had been properly executed. The novel plays heavily with Jackson's sense of ambition and pride, contrasted against his faith, but it's overall clunky. The thoughts seem unrealistic, even naive at times. It takes a master to inject realistic thoughts into a novel properly, and Robert Halpert just couldn't pull it off. To be fair, it could be worse. But why settle for mediocre?
In general, the book is an okay read, mixing various elements in a fairly skilled manner. It's not a classic, but it's worth your time if you're a Jackson fan. If you're a Civil War buff, or only looking to be one, then you're better off looking at Shaara's novels (links above); they're much better written. But if you have a spot in your attentions for Stonewall Jackson specifically, as I do, then this book is worth your time, even if it's not an outstanding book.