Well, if you have interests in World War history this movie is a must watch for you. And nobody can make you feel involved in a movie than Christopher Nolan. If you expect a lot of action, killings, hand-to-hand battles, bombings etc in this movie than this movie is not for you. But, if you want to know what the soldiers in the World wars would have gone through and want to see yourself closest to the war-like situation and experience the pain, emotions and patriotism then this movie is for you.
The screenplay, sound effects are awesome. First half is a bit slower but much stronger second half. "Action says louder than words" is what Nolan would have kept in mind while making this movie. Direction speaks for itself. In my opinion, "Dunkirk" would be nominated for Oscars this year and is a must watch for the ones who crazy about war movies.