It was by far the weakest book of the series
The two voices switching off was confusing, and the two didn't really seem all that different. Sometimes I had to look back to see who was the narrator of that chapter.
Tris and Tobias were written identically
The character's individual voices were completely lost.
I think the first two book were better.
It was difficult to believe on the relation between GD, GP and the factions.
It does not take several generations for a genetic manipulation to take effect.
Whether you are removing or adding a gene, it manifests right in the very subject you are altering.
If you want to fix broken genes, all you need to do is stick the gene right back where it came from and that's it.
Genes don't "heal" themselves. It's corrected at one time, not after multiple generations of inbreeding.
A small population with no genetic variation will only create a founder effect: the damaged genes they carry will only become more prevalent over time. They will just as likely make the defect stronger and eventually create new and perhaps even screwier genes through mutations as they would achieve any imaginary genetic "healing." If these people are such a scourge on society, the only reason it would be prudent to round them up in one place is so it would be easier to blow them all up at once.
This experiment also makes no sense as an explanation for the society being divided into factions
When you include real science in a story, you have to do research to make sure it makes sense.
To Keep reading, I imagined that all of this happens in another world where this all could make sense and that all this “human beings” in the story are not like human beings on Earth.
The POV is a bit confusing. The new characters were not well developed. The state of the world was extremely ambiguous. But you need to remember that this is Tris story. Not the Bureau story, or the city's story, not even Tobias story. Not about real science or real human beings.
This is the story of a girl that did not think much of herself and ended up saving so many people because of her selflessness.