I don't know anything about the genesis of this book, but I have to assume that Brunner produced it fast, or early, or in some other way wasn't really paying attention. I admit that I'm not a big Brunner fan (no, not even Stand on Zanzibar), but I've like his other work much more than this.
Here, Brunner has barely the germ of an idea, and does very little with it. The beginning of the book is catchy, with one mysterious, powerful stranger intercepting a mysterious, intelligent merchant. But the book never takes off from there. There are eventually aliens, and there's a token effort at some sociology. But essentially, this is a series of minor obstacles that are solved (within hours) by technology in altogether incredible ways, with all sorts of collateral damage that's barely even recognized.
It might have been an acceptable story if written in the '20s or '30s. But for a book published in 1959, it's just not nearly good enough.