Let me very clear about why I'm giving this book a low rating.
The original story, from Uncanny X-Men 141-142, was great. There were elements of Terminator, but a lot more to it than than, and Chris Claremont and John Byrne did a fantastic job with it.
This had a lot of holes in it. Yes, what I'm going to list is, for the most part, nit-picky comic book trivia. But if you're writing a book based on the comics, you should know what you're talking about.
Among the many weird moments: Nightcrawler wasn't using a sword in fights at this point, his skin isn't blue (that's fur, hence one of his nicknames "Fuzzy Elf"), the Blackbird is a VTOL aircraft so it doesn't need runways, Kitty Pryde adopted the codename Shadowcat much later than this story, and Pyro is Australian, not English. It was also odd that, as a major fight broke out where Professor X was, he just got wheeled away instead of using his powers to help. These kept cropping up and knocking me out of the story. If I can keep all this in my head, a paid professional should be able to keep up with this kind of thing.
I am huge on superheroes, and really liked the original story. There were just too many mistakes in here. In addition to the trivia stuff above, there were formatting issues throughout, like words being randomly broken up by hyphens, and lines being mis-set.
If the idea of someone coming back from a horrific future to prevent it from happening appeals (and it's a recurring theme in X-Men, see also Cable, Bishop, and Rachel Summers off the top of my head), read the original issues or a collection of them. The movie of the same name had the general idea, but a LOT of changes. This adaptation, sorry to say, wasn't that good.