I highly recommend it, especially if you can see it in a dedicated 70mm screen. There are deaths -- it's a war movie -- but gore is actually fairly minimal. The tension, otoh, is intense. Hans Zimmer scored the movie with the recurring motif of a ticking watch, and even when you can hear the watch, there's a relentless rhythm under the score. And when there's no score, it's usually because the music is replaced with something awful, like the screaming of a Stuka bomber.
The movie is surprisingly short -- just 106 minutes -- and has three intertwining sections: The Mole, about the soldiers on the beach and the mole which is the only way of loading soldiers onto the big ships, as there is no harbor they have access to and loading from the beach would require ships with a draft of three feet or less; The Sea, about one of the Little Ships of Dunkirk; and The Air, about an RAF pilot.
I do suggest you go with someone whose hand you can grab, because as I said, the movie is intense.