This movie depicts a topical and realistic situation, with the codes of most major big-budget movie. The cast is well chosen and overall does a good job of portraying what many would expect the French navy to be like.
But in my opinion, the most successful trait of the movie is its storyline, stemming from contemporary stakes, which I've rarely seen in military/tactical movies, which instead tend to focus on past historical events or on more far-fetched futuristic scenarios.
I think that's the reason the story is so compelling, and why I personally found the movie so immersive.