Let’s talk about the language shift.
There’s a long tradition of inventing words that mean other things (Burgess, say), but why use it to represent identical concepts as in our language? The author introduces the text by saying that he’s replaced most things with a familiar word for us where it makes sense to, but this is a bit false, since most of the “new” words are just 1:1 substitutions for words in our language; only a few represent unique concepts. I understand the idea that it’s a microcosmic illustration of the parallel worldtrack phenomena, but I think it’s stupid and unnecessary. There, I said it. Call Occam’s razor and the Pythagorean theorem what they are; we’ll take for granted that the other narratives will have different names, but they’ll also have completely different languages, so it won’t even be relevant. Duh.
The plot is somewhat linear, with the end state pretty typical for Stephenson’s work; he does like the protagonist as a pawn that saves the day sketch for a story. It looks in that regard like a structure similar to his earlier works, but with a maturity in writing that those lack.
In the end I’m somewhat torn by the story. I’m irritated by the toying with words, the platonic theme was a bit heavy-handed, but the story was readable, had a few nice twists along the way, and kept my interest. 7/10.