This movie feeds itself by the emotional and amazing historical context of the Dunkirk miracle.

However, Nolan attempts a non chronological line to convey the story of the soldiers and all the situation they've been through during this time. This creates a sense of blurriness towards the message behind the story and the plot progresses continually on a obvious outcome.

Also, thrilling scenes are the main tool used to gather the audience's attention, because the story itself is not well constructed (you can feel something is missing), and at certain point you already know that everything is poorly connected somehow.

Still, the historical background is pretty interesting and the use of portraying the civilians point of view, was a really good way of involving the emotional and nationalistic character of the time. Unity, was key!

Overall it was a decent movie, with good scenes and amazing action buildups, but it still lacks personality, specially in the screenplay.