There is no role Oscar Isaac cannot play.
As a romance movie, this film is very below average. I was never invested in the love triangle, and thought there was more in the plot to care about.
As a war drama, this movie is much better. It doesn't shy away from gruesome sequences of violence, but it also mixes in tense scenes and great escapes. It handles it's sensitive subject very well, and you can tell the actors care about the story they are telling.
It has some great long shots of the city and the streets, and the scenes in the mountains are shot both tightly and frantically where need-be.
'The Promise' is a worthy war drama with a really lousy love triangle.