I think it was pretty evident that Serwa's "song" at the end was supposed to be magic - she was gonna tear the place asunder.

Anyway, I think Ishterenbinth sections were my favourite in this last book. Sorweel is my favourite character introduced in the second trilogy, so watching him become something greater was cool. The Nonmen were wonderful; I felt sad that the Lastborn died, though. It was also interesting to get POV from Serwa, which made her come across as more sympathetic (why she treated Sorweel so cruelly revealed, etc.)

I'm curious about what the finale implied regarding her and Sorweel, though, what with her thinking of him as being "real". I got the feeling that their romance affair is gonna be a thing.

I think, when people talk about how the son of the survivor can be a Dunyain who feels, they forget that all Dunyain can feel. Moenghus admits as much; Kellhus, in The Great Ordeal, seems to show genuine care for Esmenet. The survivor himself chooses a defective child because it is his son. So I  don't think the child is different in that regard; he just isn't as well educated in the Dunyain Doctrine as the rest of them were.

Another interesting thing to note is that the Anasurimbor seem to be best Dunyain. Child Kellhus, in his flashbacks, seems smarter than the rest. And Moenghus calls for his son for his plan, rather than any other Dunyain, and he isn't exactly the sort that'd do that out of sentiment.