Dunkirk is a success in almost every way. I've liked every Christopher Nolan film I've seen (Dunkirk is my 7th), with Insomnia and The Dark Knight at the top, but here, I think he uses his bag of tricks not just to show off, but to help the audience along, which turns out to be an excellent idea.
There are three basic stories in this telling of the Battle of Dunkirk, land, sea, and air. The sea is the most famous part of the story ... the civilian boats coming to rescue the troops are iconic reminders of the event. The troops waited on land ... meanwhile, aircraft provided cover for the boats. Nolan's structure for telling those stories is fascinating and effective.
I tend to get lost in plots, and in something like Nolan's Memento, well, confusion was partly the point, wasn't it? But I never got lost in Dunkirk, despite the fact that Nolan diverges from "real" chronology. The soldiers were on the beach for a certain amount of time, the boats took a certain amount of time to arrive, and the planes had their own timetable. Nolan mixes and matches in order to emphasize the importance of each story, perhaps most clearly in the flight of the fighter pilot played by Tom Hardy. Nolan doesn't worry about making Hardy's story match up correctly with the others in terms of chronology. Instead, he matches the dramatic arc for the pilot with the dramatic arcs for the other stories, so that Hardy's adventures make dramatic and emotional sense, even if they are not "correct". This video from The AtZ Show does a fine job of getting at this:
Dunkirk is intense from start to finish ... I think it benefits from a relatively short running time (at 107 minutes, it's Nolan's shortest feature). And I'd like to give a shout out to Hans Zimmer, whose score got an Oscar nomination (the film got 8 nominations total, and all of them are reasonable).
A couple of notes I couldn't fit anywhere else. Tom Hardy is a favorite of mine, and when we first see him, almost his entire face is covered. All we see are his eyes, yet I immediately thought to myself, hey, it's Tom Hardy. And I didn't even know he was in the movie. Also, when I think England, I think tea drinking, and there is a lot of tea drinking in this movie.
Finally, here's another great video explaining something I couldn't come close to putting into words: how Zimmer and Nolan add to the intensity of the movie using something called ... well, watch this:
#269 on the They Shoot Pictures, Don't They list of the top 1000 films of the 21st century.