The best part was the "Realistic" world building. It was a good movie but can't hold a candle to Predestination (2014) based on works of Robert A. Heinlein. It's a consistent time travel story that got predictable due to all the right reasons of being airtight and it's impossible to spoil.
Spoilers!!!
A guy who fails at his assignment to stop the terrorist responsible and get disfigured and after a surgery he goes on a final assignment to meet himself at a bar who is given a chance by himself to kill the person he hate the most and face no consequences. The two of himself goes back in time to meet herself only to impregnate herself by himself who's child is taken to the orphanage she grew up as herself before herself became himself and tries to go the extra mile by helping himself in the previous assignment against the terrorist which he doesn't totally succeed at and is retired to find out that the terrorist was actually doing good stuff and is also himself.
End of Spoilers!!!
I just included the entire plot above.
"The Snake That Eats Its Own Tail, Forever and Ever . . . I know where I came from—but where did all you zombies come from?"
That's a quote from the book. It explains the whole story.
Yes, I know Predestination is a good movie. I will try to make a review of that movie soon. And yes, I think his problem was that it became predictable, since I could sense its end at a certain point not very advanced in the film.