It was confusing and frustrating. But that's war.
Not a big fan of the tick-tock sound in Zimmer's score, feels like a bit of a cheap grab at tension.
Really love the subtle editing at the very end.
Edit: On second thought, Nolan interweaved those three time periods so successfully, hiding its many logical flaws within his writing and the film's editing and essential breaking his realism in order to maintain it, that I am going to move this up to a 10. It is peculiar; usually one of my qualms with Nolan's films is the (slight) unraveling of his narratives upon further thought, but with Dunkirk, he embraced his films' recurring flaw by allowing Dunkirk to be edited non-linearly, by not sticking to a set of predetermined and self-instructed rules (as seen in Inception), letting the film be edited as only the cinematic form can allow, illogically. In a way, he did still set a rule for himself: as the film wants to cinematically depict the warfare experience, the editing should reflect war's confusion, but also its inevitable, swift, and painful fluidity. A complete success.
Now the rating can only go down on rewatch which is never a very good situation.