Short version: Oscar-bait, deservedly. Go see Dunkirk in 70 mm. Well worth your time.
Slightly longer version: the movie operates in three interlocking circles — one story takes place over a week, the second over a day, and the third over an hour — and while you can keep track of what’s going on where Dunkirk is a movie where you have to pay attention. It is also a movie where everything is stripped down. Even the previews were perfunctory. It’s going to be surprising if this movie doesn’t get a Best Picture, Best Direction, and/or Best Original Score nomination at the Oscars… but it shouldn’t be surprising if it doesn’t get Best Original Screenplay, because there isn’t much in the way of conversation in Dunkirk.
Dunkirk is a good movie, but not a fun one. Nolan did a dang good job with this one, but he wasn’t doing it to make his audience feel good. Don’t make this a date flick.
Also, you will need to find a theater that has good speaker. This movie is loud, both in explosion/gun sound and soundtrack. My local theater failed the test.