This is good and worth seeing in the theater... but....

Rating: Null/10 (19 January 2020)

Everyone has said it all. Technically this is incredible.
But... I don't really go to movies to be blown away by their technical prowess.
It matters, of course, and I fully appreciate what was done here with the "one take" aspect of how it was filmed. It contributes to the environment the audience is living in. Someone else wrote it as "immersive" and that is as good a word as any.
But I guess what I go to moves for in part are characters and story. And in this respect maybe the film falters a little. I don't really feel like I ever emotionally connect with the main character. It could very well be that the way he acted his role is intentional. It's like he's only 80% there, and the remaining 20% he is hiding or protecting. Regardless, I just don't really feel like I ever know him or (to be honest) like him all that much. He is to be sure a hero and does amazing things. But... I'm just left kind of cold by him.
Anyway, the one character I did totally connect with is played by Andrew Scott. Yes! Andrew Scott! Our friend Moriarty from "Sherlock" who plays a relatively minor character named Lieutenant Leslie in this film. He's maybe on for 5 minutes. I would love a movie about him. He's fascinating and where the main character is only (and at best) 80% there, Lieutenant Leslie is 150% there. His presence is that enormous.
This is not to detract from our main character. The actor who played him is in nearly every scene and I can only imagine the physical and mental challenges he went through to make this film.
The music is good but at times became overwhelming. I don't need the score to help me know that we're in an emotional scene. I am mindful that I may be in a minority here. Most of the time the music was not intrusive, but at times it was.
I wanted to mention there are some scenes that visually disturbed me greatly. War is awful and WWI and the trenches was just... awful. I did not get the feeling that there was gratuitous violence, but to be honest I wish I could unsee some of what I saw.
Still, I'm glad I saw it. I recommend it.