I haven't read this in decades, but I remember it well enough that I'm going to comment. I think the story is entertaining, but it's badly written. I doubt I'd be able to read it now, my tolerance for shoddy writing having been greatly reduced.
The use of Strachan as a narrator was an obvious and tempting device, but Shute didn't play by the rules. It was fine for him essentially to transcribe Jean's ordeal in Malaya as she related it to him, but after that he showed an impossible knowledge of Jean's activites in the Far East and most especially in Australia. We're supposed to believe that Jean even wrote in her letters to him about how she ended up bruised after snogging with Joe? Moreover, at times Strachan even seemed to be able to tell what was going on in Joe's mind! Generally speaking, the detail and knowledge of minutiae was impossible at Strachan's distance. Shute used Strachan to be able to comment on Jean's beauty and pluck and intelligence, etc., without using the direct authorial voice, but he didn't let it constrain his narrative as he should. Fail.
And just a couple of preposterous plot points. At the same time that Jean inherits a fortune, uses it to travel to the Far East and learns that Joe is alive, Joe learns that Jean was single, wins a pool, and travels to London? Oh, c'mon.
Then, there's the absurd closed economic system that Jean was able to parlay on the basis of a shoe factory employing four. The World Bank missed out when she wasn't made Czarina for life. I expected Willstown to beat Sydney to an opera house, at the rate she was going. Shute had a story he wanted to tell, but he left reality in the dust.
Add to that wooden prose and unnatural dialogue. I won't go into detail about the rampant racism, but Mrs. Boong fails to charm, even before we see the attitude toward the aboriginal people in Oz. Even if you tolerate the cringe-inducing moments as a reflection of its time, it's not worth such a flawed book.
I'm calling Shute a hack who no longer deserves to be read.