(Not parent)

The second half differs dramatically in tone. If you were really into the specific feeling of the first half, it is very jarring.

I found the whole thing very interesting and enjoyable, but I can imagine being excited for more content similar to the first half and being disappointed by the drastic shift in scale/tone/focus/etc.

That's definitely true.

I saw the book as two parts:

I: We have a problem, how do we solve it?

II: What are the (very long term) consequences of how we (and possibly others) solved that problem?

From that perspective, it fits pretty well, though yes, the tones of the two parts are decidedly different.

Wouldn't mind hearing from OP on their specific concerns.