Well, I thought that Dunkirk was for the most part totally fantastic. There were a few bits I didn't like - a couple implausible nick-of-time rescues and a couple on-the-nose heartstring-tuggers but they stood out in a way they wouldn't have in a lesser film because Dunkirk was so relentless, tense, and apocalyptic. The convoluted structure, it now seems, served the non-academic, non-trivial purpose of making the climax essentially last for the entire running time of the movie and it more or less worked. And the music...I've been indifferent to Hans Zimmer in the past but this score, which reminded me of Vangelis and Robert Simpson's ninth symphony, in conjuction with all the incredibly loud and sharp gunfire, grinding metal, surging ocean, and roaring engines, was crushing and constantly ratcheting up the tension beyond where I thought it could be sustained.
I'm still digesting the aerial combat scenes, which I have been eagerly anticipating for quite a while. On the one hand, they lacked the speed, kineticism, and extreme stunt flying of some other classic movie dogfights using similar techniques of in-camera footage of real aircraft with a bare minimum of special effects but I'm starting to think that worked to its advantage. Maintaining situational awareness and understanding spatial relationships, being parsimonious with fuel and ammunition, and patiently leading a moving target is kind of what air combat is about.
As for period details - real Spitfires and .303 SMLEs, excellent mocked-up and RC miniature Bf109s, He-111s, and Stukas, no complaints there. The destroyer in the channel looked a little modern (it's actually French and from 1957, I discovered) but it was real and had hundreds of people on it, and better that than some CGI eyesore with lines that more superficially resembled a '30s Royal Navy warship.
ps i had to look up which one harry styles was and i'm still not entirely sure