In one corner: the lunar colony's oppressive government, comprising the Warden and dozens of armed guards who enforce his will.
In the other corner: a beleaguered band of revolutionaries with no resources except for... the support of the entire population, the only AGI in existence, and complete control over the colony's automated infrastructure.
Will the revolution succeed??? It's not exactly a nail-biter.
Heinlein does give the novel some stakes eventually; the real antagonist is not the weak lunar government, but the Earth government backing it.
The tone of the novel doesn't match the title. Despite how much the narrator describes life on the moon as difficult and dangerous, the "Loonies" (heh) seem to waltz through life pretty easily. All the characters are presented as emotionally well-adjusted and nobody seems to be traumatized, so talk of how harsh their circumstances are feels glib.
Similar to Ayn Rand, Heinlein casts his characters in a positive or negative light based mainly on whether they have a sort of can-do, action-oriented attitude or whether they're merely "yammerers". He's also pretty optimistic about the possibility of achieving happy ends via deceptive, manipulative, and (occasionally) murderous means as long as his plucky heroes are the ones employing such means. Combined with the government-is-the-root-of-all-evil political bent, it comes across as a pretty simplistic fantasy about how badass society would be if the right people - people who think like the author does - could just work up the verve to take power. But it's still fun to read. (And there's something cute about a bunch of libertarians calling each other "comrade".)
One thing I enjoy about reading older sci-fi is that you get to see imagined futures that were influenced by a different set of cultural and moral assumptions than the ones we hold today. In Heinlein's lunar society, sexual objectification is a sign of respect: upon meeting a woman, to be polite, the man must ogle her and whistle. The culture also features "line marriages" with multiple husbands and wives, where a teenager who's been "opted" (adopted) as a spouse is expected to sleep with all the other spouses, some of whom are elderly. Because these ideas neither fit our moral sentiments nor seem like natural progressions from current society, an author writing today would be less likely to come up with them; this adds an interesting element of strangeness.
Finally: it's super adorable how the self-aware computer's way of addressing Manuel changes as it makes more friends over the course of the story. "Man my only friend" becomes "Man my only male friend" becomes "Man my first and best friend".