As with Starship Troopers, Stranger offers up a buffet of thoughts and philosophies, provoking quite a bit of introspection, if not agreement. The premise of the novel is that a human born and raised on Mars is brought back to earth, juxtaposing human (mainly North American, but there are smatterings of Islam) culture to the fictional Martian way of thinking. Much of the difference, it seems, stems from humans having two biological sexes, while the Martians have only one. 
 The problem, the same problem I had with Starship Troopers, is that some pretty awful things are presented as Truth, delivered by characters who are set up all-knowing (or close enough) Truth Tellers, without even so much as the balance of a dissenting voice. In Starship Troopers, what stood out the most for me was the proposition that we could solve our social ills by reinstating corporal punishment (from babyhood and into adulthood). Here, my big issue had to do with the novel's attitudes toward women. 
 Women are treated rather atrociously throughout the novel. There are brief moments where Heinlein seems close to acknowledging this, such as when he has Jill bristle at being called "little lady" by Digby (and Harshaw underlines the point by bringing it up again, mocking Digby by using the term himself). This comes so close to being a condemnation of the casual infantilizing of women that was so common in the 50s and 60s. The problem is that Digby is far from the only character who does this (and his "crime" seems to be more the awkward repetition of the phrase, rather than its use in the first place). Throughout the novel, women are referred to as "little girl" (and equivalent terms), and generally treated like some odd cross between child and servant. 
 But the true shocker is when Jill claims that, 9 times out of 10, women are at least partially to blame if they get raped. This is presented as instructional, teaching Mike (the "man from Mars") about The Way Things Are, and the statement is never challenged. It is simply dropped as a logical and accurate observation, one that anyone other than a cultural newborn like Mike would know, if they gave it any thought. 
 Even once we get to the nest stage of the novel, where Mike becomes a messiah figure leading his disciples in what is presented as a perfect human state, when the male and female characters are at their most equal, the banter still reveals deep prejudices. As do the assumptions made by the characters, and how many of the duties are arranged (it is women who do the bulk of the "service" work, such as running Harshaw's bath). 
 The problem, as with the issue of corporal punishment in Starship Troopers, is that Heinlein presents himself as a philosophical forward thinker, capable of seeing through the cultural prejudices that blind most people. And yet, when it comes to certain issues, he seems just as unwilling to consider alternatives as anyone else. 
 The issue of homosexuality in Strangers (and in Heinlein's broader body of work) is a much more complicated discussion. On the surface, Strangers seems as indisposed to challenge the social mores of the 50s and 60s with regards to homosexuality as it is with regards to women. 
 There main pull-quotes are: 
 -Jill is very concerned that Mike, being from genderless Mars, might not know not to accept advances from gay men, so she issues a rule against it. She is relieved that Mike chooses men for his inner circle who are very masculine (and women who are very feminine), emphasizing both her ideal of sexual binarism and her distaste for homosexuality. 
 -When Mike allows Jill to see women through a man's eyes - as sexual objects - she is relieved to find that she goes back to viewing women in a non-sexual way once she sees them through her own eyes again. The narrator says that "to have discovered in herself Lesbian tendencies would have been too much." While the argument might be made that this is all from Jill's perspective, a remnant of her somewhat conservative upbringing, the view is never challenged (even though Jill's views in other areas are being challenged in nearly every scene in which she appears - first by Harshaw, then by Mike). 
 -When Ben tells Harshaw of his visit to the nest, he is forced to admit that, in the nest, men kiss men. This, he assures Harshaw, is "not a pansy gesture." Harshaw then talks about the Kiss of Brotherhood, and a fair amount of effort is put into reassuring themselves and the reader that there is nothing homosexual about the expressions of physical intimacy between men in the context of Water Brothers. 
 But then there are hints of a more accepting perspective. Jill is no Lesbian, we are assured, yet her Kiss of Brotherhood with Patty is described as "greedy." Not only that, but men are expressing physical intimacy with each other, and frequently doing so while completely naked. Like I said, it's a complicated issue, and one that I don't feel prepared to parse out. I did manage to find a good article on Strange Horizons that tackles the issue. 
 My final complaint about the novel is that Harshaw feels far too much like an author insert. He is an outsider, a prime mover, and he is a dispenser of wisdom through nearly the whole book. His role is almost exclusively to drop down into the other characters' lives, tell them everything they've been doing wrong, deliver snippets of great wisdom, and swoop back into the sky. Pages upon pages are devoted to his rants, and all the other characters fawn over his superior logic and wisdom. At one point, a character exclaims that Harshaw is the only person to be capable of groking Mike's mysteries without first having learned to speak Martian. It's not until the very end that he is taken by surprise, and then it's only to pump up Mike's own specialness and to set Harshaw up as his spiritual successor. 
 The novel feels rather uneven, divided into two (arguably three) very clear parts that struggle to fit together as a whole. Still, I found the novel very interesting and thought-provoking, despite its flaws.