It's really the only Leonard novel I've read that I really liked. The film does a good job capturing the feel of the novel (helped, no doubt, by Leonard co-writing the screenplay).
It made me wonder, though, where the concept of "rich industrialist has problems that turn violent" set-up for crime novels originated. John D. MacDonald, of whom I've written much, used it quite frequently, but he's hardly the only one. It would be interesting to try to figure out the origin, but I honestly wouldn't know where to begin.
At any rate, read the novel or watch the film - they're both good.