Strata

I see the creative potential, even elements that will eventually become the Discworld, but this was pretty messy. I sincerely hope Pratchett's later forays into science fiction are more fun than his early ones, considering how entertaining his fantasy series is. 
Similar to The Dark Side of the Sun, (a moment here, vs a more fully realized issue in the earlier book), this hints at an intensely problematic motif of the ‘cheerful slave' replicated in the robots of the future. 
Both The Dark Side of the Sun and Strata seemed to flirt dangerously close to moments of black face.
On the other hand, he seems to be trying to say something about the limiting and harmful effects of xenophobia. 
Given what I read in Terry Pratchett's bio, reading, looking up to the previous generation's early modern sci fi, it's not a surprise that he inherited the inclusion of questionable ideas. 
I'd love to just chalk this up to being written 40 years ago, but that does feel like giving a favourite author a free pass.
 I am grateful that especially in the Vimes books in the Discworld series, Pratchett over the years seems to be taking a more thoughtful, nuanced approach in examining xenophobia/racism/prejudice.  
As to the narrative, you kinda just have to go with it...fair amount of info dump, or I guess more just casually tossing world building at you the explanation coming as you go along. 

⚠️ Xenophobia, cannibalism