As an action thriller, I'd give this film maybe a 2/10. But that is not what it was intended to be. The ads and marketing of the film falsely suggest this is an action film, and that is a great disservice both to the film and to the audience. I suspect that the film's rating would be higher had the marketing been honest. It is almost the opposite of action: it's a quiet, introspective film. I didn't expect a thriller and so I wasn't disappointed.
As usual in this kind of film, there is not a lot of backstory. We never find out exactly where Jack came from, how he found his job, why he could take such a job, etc. But that's not really the point. We never really find out much about the back story on the other characters, either. I think we actually found out more about the priest.
I enjoyed the film in about the same way I would enjoy a short story, which focuses on a few points rather than furnishing a history and full explanation.
As usual in this kind of film, there is not a lot of backstory. We never find out exactly where Jack came from, how he found his job, why he could take such a job, etc. But that's not really the point. We never really find out much about the back story on the other characters, either. I think we actually found out more about the priest.
I enjoyed the film in about the same way I would enjoy a short story, which focuses on a few points rather than furnishing a history and full explanation.