It's pretty incredible how much ground this covers! However, the ordering feels a little confusing to me.
One example is in chapter 1. It talks about symbol exporting based on platform type, without explaining ELF. This is before talking about while loops.
It's had some interesting nuggets so far, and I've followed along since I'm familiar with some of the broad strokes, but I can see it being confusing to someone new to systems programming.