I Will Fear No Criticism Dept.
Me not being a Heinlein fan, I found this essay provocative, but ultimately I couldn't swallow it:
Locus Online Perspectives » The Joke Is on Us: The Two Careers of Robert A. Heinlein
... it is not only in the juveniles that one can observe Heinlein’s efforts in the late 1950s to revisit old haunts in a humorous fashion; for 1959 also brought the publication of the story “`All You Zombies –,’” wherein Heinlein returns to the theme of multiple versions of oneself interacting by means of time travel, first effected in “By His Bootstraps,” but adds a sex-change operation to further complicate matters and transforms a thought-provoking exploration of the implications of being a “self-made man” into a fun-filled sexual romp.
I don't know about you, but "fun-filled sexual romp" is the last set of adjectives I would use to describe a story that comes closer to the existential horror of Philip K. Dick than almost anything else Heinlein wrote. You might as well call Hellraiser a comedy of manners.
See, I like the idea that Heinlein was testing his audience and seeing how far he could get away with "being Heinlein", as it were. (The essayist is spot-on in that the number one character in any of his works is the author himself.) But even that doesn't go halfway towards explaining nonsense like The Number of the Beast.
I also agree that a lot of the military-libertarian SF that sprung up in Heinlein's wake can't be pinned exclusively on him. Why do that when you can just blame the very living authors responsible for such dreck?
