Having lived under a Middle Eastern-style despotry and aboard a clannish trading vessel with a gypsy-like attitude toward strangers, the hero then makes a transition into an British style navy where again he must learn a totally new way of life. He not only learns Western values, he learns his own birth identity and the role he can play, should he choose to, as a citizen of the galaxy.
The book is quite a broadening experience, for its hero and for the reader, and Heinlein's research and fidelity to the systems he describes is impressive. Except for the space element, the story might have been set on 19th century Earth. One of the best aspects of Heinlein "science-fiction" is that it is not alien or technology driven, but plot and character driven. Some of Heinlein's books have the flaw that they lack endings. Yet this story is fully integrated and does not disappoint. Do not be put off by the fact that the main character is an adolescent. The book is fully suitable for adults and I have read it three times. Heinlein's love for humanity, his cosmopolitan sophistication and his nevertheless unending advocacy for the superiority of universal liberal values show that Heinlein himself most assuredly deserved the title Citizen of the Galaxy.