I find myself feeling torn about this book. There's a lot of interesting ideas here but the book just never quite ended up being truly enjoyable for me.
The story is divided into two parts in two different timelines, labelled John's World and Skynet's World. The former picks up right at the end of Terminator 2, depicting what happens to Sarah and John as they escape from the cops who swarm the steel mill and decide to head down to Argentina to stay with some friends. From there, the story spends a while establishing that Judgement Day was only delayed, not completely averted, as some notes and information survived, and there are enough other employees of Cyberdyne to continue the Skynet project.
The Skynet's World timeline also picks up during Terminator 2, but shows an alternate version where John and Sarah decide to bug out south with the T-800 rather than attack Cyberdyne. It's clearly meant to be the original timeline that leads up to the first Terminator, as it splits time between showing the development and birth of Skynet and the way John develops into a leader after Judgement Day and starts to unify South American militias into the human resistance. This is a pretty cool idea, because aside from a few scenes in the first film and some material in the novelization of the second, the future war hadn't really been depicted. Terminator Salvation would later try to do something similar, but I liked a lot of what this did better.
The main issue is that it feels like it's rushing through what could make for a fun trilogy of novels all on its own. By the end of this book the story has already reached the eve of the final battle in 2029. There's a lot of time skips and in general the story moves faster than I'd like. This is also true of the Skynet side, as while seeing Skynet's birth is pretty cool, things then jump to it creating the first Terminators far too quickly. It makes me worry what the series will do with this part of the story in the next two books, since it seems to have used up most of its material already.
Rushing is also a major flaw of the John's World story. The book opens with a prologue showing a more advanced liquid metal Terminator and a group of augmented humans both getting dropped into Mexico City in 2001. About halfway through the book, things finally catch up as the humans rescue John and Sarah, who've been living in Mexico City and running an internet cafe, from the new TXA Terminator. What follows is a series of action heavy chase sequences culminating in another raid on another Cyberdyne facility. It's too derivative of the film this is acting as a sequel too, and it also suffers from introducing five augmented humans and then offing half of them, giving the reader no time to get invested in any of them. The advantage of the classic Terminator twosome trope the movies usually use is it allows the audience to focus on getting really invested in a few characters. Also, this augmented humans concept is interesting, but I liked it better in Dark Fate where it was clearly cybernetics and an interesting twist on the man machine conflict, while here how the augments work is vaguer and doesn't thematically resonate as well.
I'm also not sure how to feel about the changes to time travel this story has. Terminator, in the first two films, has the question of whether time is fixed or changeable, with the first movie being a time loop and the second potentially breaking the loop. This book instead introduces the idea that the only options are loops and branching timelines. Some travel can create a stable loop, and if it doesn't, as is the case with the T-800 in T2 and the augments here, it creates a new timeline. It's not inherently a bad idea, and I feel like the Terminator franchise is best approached with a multiple futures mindset if you want to even remotely have things past the first two films make sense, but somehow knowing that going back in time just branches off a new timeline doesn't quite work for me. It's partly changing the rules from the films and partly the "only the main reality counts" issue with multiverse stories.
Overall, there was some fun stuff in this book. I think I enjoyed at least half of it, though even if the parts I liked I found the writing a bit of a letdown compared to the novelizations I've been reading. Also, the parts I didn't like made up the climax of the novel, which definitely hurt. . There is an interesting twist at the end of this book, so I'm left curious to continue the series but hesitant as I'm not sure if it will improve.