Skylark Series/YMMV


 * Designated Hero: The Kondalians have practically no traits that would be considered sympathetic by modern readers. They have no concept of democracy, race-based slavery is unquestioned, they've been at war for 6000 years over ideology, are Social Darwinists who believe themselves a Superior Species, and admit to having no concept of mercy. All in all, they are no better than the Mardonalians; the only reason they are considered good is because they were nice to the heroes.
 * Context on that last: it is explicitly Lampshaded in the text that had the Mardonalians dealt with the Skylark party in good faith, Seaton could entirely have seen himself ending up helping them to exterminate the Kondalians. Remember, the Skylark originally landed in Mardonale. The fact that the Mardonalians didn't offer genuine hospitality but defaulted instead to treachery and attempted murder as their first option when dealing with a group of strange castaways, is what ultimately dooms their civilization. So the point that 'they are no better than the Mardonalians' is not accurate; the entire plot of the endgame in the first novel is driven by the fact that the Kondalians and the Mardonalians are clearly on separate ethical levels. Admittedly those levels are 'bad' and 'worse' rather than 'good' and 'bad', but that's still a legitimate difference.
 * The Kondalians do have two virtues that modern-day readers would respect: they are both completely honest (Kondal has virtually no concept of intrigue, let alone any actual experience at it) and entirely honorable. And not just in the Proud Warrior Race Guy sense of honor but in the sense that they consistently treat everyone how they expect to be treated and always deal in good faith until after it is apparent that the other party is not.
 * Unlike the Mardonalians, and the villains generally in the series, the Kondalians are not Absolute Xenophobes, but willing to co-operate peacefully with other planets. That said, they are typically portrayed as a species of Proud Warrior Race Guys, with a strong whiff of Barsoom. They're very flawed good guys, and they do occasionally get called out on their warmongering by the human protagonists.
 * Regarding the 'no concept of mercy', it is important to remember that the Kondalians have spent the past six thousand years locked into a war of extinction with an enemy who is not only even more merciless but also infamous for its treatment of prisoners. Many readers consider the Kondalians be doing no worse than human beings would after that kind of experience.
 * The series ends with the Crown Prince of Kondal essentially admitting 'We are complete barbarians by the standards of the civilized galaxy and we're going to have to change, or else we'll be left behind.'
 * Fair For Its Day: By modern standards, the treatment of Crane's Japanese servant Shiro is pretty awful. He's brought along to do all the menial work, he acts in a servile fashion, he speaks only broken English (until a language-teaching machine is invented early in book 2), and in general he's a walking stereotype. However, by 1920s and 1930s standards the part where Shiro is allowed to demonstrate any intelligence at all, shows physical courage in the face of danger equal to the most stalwart of the heroes, actually speaks in intelligent and cultured English the instant he learns the language (and even his prior speech merely had bad grammar, not pronunciation or content) and has his employer treat him as a close personal friend and confidant and consider any injuries done to him equally as worthy of avenging in blood as injuries done to any of his other friends or loved ones is infinitely better treatment than a Japanese man could expect to get in popular entertainment of that era.
 * Magnificent Bastard: DuQuesne.
 * Older Than They Think: A "dark star", essentially a black hole, and mushroom clouds produced by the atomic/total conversion of explosive shells. Both in The Skylark of Space, published in 1928.
 * Early drafts are said to go all the way back to 1916. That is sixty years before Star Wars.