Playing with genetics is fun.
Playing with genetics accurately is extra fun (seriously, the science in this is a+).

So I'm not quite sure what didn't click for me in the book. I overall enjoyed it but it's definitely my least favourite Blake Crouch book. Dark Matter and Recursion felt like they had far higher stakes and I found myself unable to turn away. Upgrade, by contrast, was remarkably predictable and had very little suspense. This is possibly because that's how our narrator experiences the world after his upgrade. This was a disappointment to me since I'd gone into the book expecting a fast-paced thriller full of morally grey and complex characters... which this had the potential of being, but didn't quite pan out for me.

All that said, I appreciated many aspects of the book. Not only is the science plausible, but the writing is lovely and includes scenes reminiscent of both the Island of Dr Moreau as well as The Stand. Recommended if you want to contemplate the ethics of playing god to save the world and don't mind a semi-predictable action/adventure plot. 3.5 stars rounded down.

More thoughts here: https://youtu.be/PzkEfMJg21M