Its kind of fitting that Jack Vance wrote a story in which the use of language is key. After all, if any living writer deserves to be called a wordsmith, its Vance. The Languages of Pao is one level a fairly standard sci-fi adventure - young prince robbed of his birthright by an usurper, and spirited away for safekeeping, where he learns the necessary skills to reclaim his throne. That last sentence, while not actually incorrect in any way, however bears only faint resemblance to the story in fact told.
There are so many quirks and grey areas here that you are always a little off balance - for instance, in the opening paragraph or so we are told that on the quiet, rural planet Pao, the standard methods of population control are forced resettlement and infanticide, which is widely accepted. The story is truly about language, and how language affects the way we think, and therefore act. New languages can be created to instil desired traits in those who speak them, and a populace altered as a result.
In this frame a rousing adventure is told, of Beran Panasper, the rightful Panarch of Pao, and his conflicts with the usurper Bustamente and enigmatic sorcerer Palafox, but the theory never goes away, and nor does it cause the book to drag (although at 170-odd pages, it is only a short read to begin with).
Vance has written a truly sci-fi tale about ideas here, presented through a fairly standard storytelling medium to make it accessible. It is well written and gripping, although the dialogue is perhaps not as "Vancian" as his later works. Some scenes are striking: there is one which clearly references the appearance of the gom jabbar testing in Dune: except that Pao was written in 1958 and Dune in 1965, so it appears that Herbert likely read this story and expanded the concept greatly.