I have just read this book back-to-back with another Dick Francis written more than 30 years later, and I can honestly say that with one minor exception, this one seemed as fresh as the more recent book. (The one exception being the hero's courtship of his girlfriend, which seems strangely formal by modern standards.)
The central story, the mystery of who killed a leading jockey and why, is compelling and I didn't guess the villain until he was confronted. Along the way, the hero tangles with a protection racket and escapes a gang of murderous pursuers in a dramatic way, taking advantage of the fact that he's riding a top steeplechaser - but perhaps his greatest challenge is a weekend in an upper-class household...
Try reading this alongside one of his more recent works and see what YOU think...