I'd hardly think so. Editor John Ordover solicited Sheckley to write a Trek novel because he was such a legend. At the time he did Shadow Lord, Laurence Yep had only three prior published novels and six stories.
According to Wikipedia, Laurence Yep is a Chinese-American writer who's written mostly fantasy, historical, and young-adult fiction focusing largely on Asian culture and folklore and exploring characters who feel like outsiders. His interview in Voyages of the Imagination says that he wanted to write a book focusing on Sulu as a Westernized Asian in the future and to put him in an alien society that paralleled Japan in the Meiji era, when the feudal traditions were falling prey to modernization and Western influence. From that perspective, I don't think it's a bad novel at all, just very different in its emphasis. It doesn't quite fit the Trek universe as we know it, because fitting the Federation into the historical analogy means ignoring the Prime Directive and having the mission be to actively push the feudal society to a 23rd-century level. Indeed, the novel inadvertently functions as a textbook illustration of why there should be a Prime Directive, because it's all about the problems arising from the attempt to force modernization on a culture that doesn't desire it. It works better if you look at it as kind of an alternate-universe story, a cautionary tale of what would happen if there weren't a Prime Directive.
Honestly, I should probably reread Shadow Lord. When I read it in the past, my only referents for a feudal system like the one shown were European, and I probably imagined it in that vein. Now that I'm more familiar with Asian and Japanese history, it might give me a new perspective on the book.
