"Freedom is a hard habit to break." 
 Geared more toward a YA audience (before there was such a distinct genre categorizing of said audience), Citizen of the Galaxy centers around the theme of slavery, cultural development, and the meaning of freedom. 
 It follows a young boy named Thorby--an unbroken slave being sold on a distant planet--as he is purchased by an old beggar. This beggar is far more than he seems, and recognizes in Thorby not only his future potential, but the possibility that he's come from a free world and may still have family left alive somewhere. 
 Heinlein's prose is enthralling. It's clear he's exploring some deep and difficult topics, but he doesn't postulate any easy answers--which makes the premise all the more believable. The characterization comes through deft and strong, even in minor side characters. And Thorby himself, for all his training and cleverness, remains endearingly innocent to the point of obtuse. Readers can't help but want to see his story have a good ending. Or at least, a conclusive one. 
 The pacing is a bit sluggish at times, but the cultural nuances and politics that occupy much of these periods of slow-down are often intriguing enough to make up for it. And the worldbuilding is impressively rich, without being overwhelming. 
 Really good overall, but the ending was pretty loose and anti-climactic. I guess I was hoping for more of a showdown, and less of an acquiescence to a backseat role in humanity's speculatively never-ending struggle with human trafficking.