A crew of spacefarers on a diplomatic mission crash-land on a planet many times the size of earth (but less dense, so it retains earth-like gravity), leaving them stranded, pursued by enemies, and almost 40,000 miles from their hope of rescue. As a premise, this sounds promising, but Vance really underdelivers; his trademark dialogue (superlative), and creation of exotic cultures is present in spades, but the book lacks the sense of scale (as appears in, say, Bob Shaw's 'Orbitsville') and so leaves this reader wondering why the planet is so big when the narrative makes little enough of it.
Compared with other travelogues Vance has written (Eyes of the Overworld and Cugels Saga are the obvious choices), this book doesn't stand up well: it's an early work and you can tell, as he is plainly still developing the skill and style which would flower in later books. The ending feels rushed and is, overall, just unsatisfying in comparison with the author's later work.
If this was any other writer, I'd give it four stars. For vance, three and a half because we know that he wrote other - much better - books later in his career.