Haven't seen it yet, but it does sound as if it's basically a fairground ride, and the 1958 movie Dunkirk, made by Ealing Studios under the great producer Michael Balcon, with John Mills, Richard Attenborough and Bernard Lee, is probably better -- relatively low-budget, but character-driven.
http://www.imdb.com/title/tt0051565/
Though I was quite pleased to see from the trailer and publicity that Nolan's film does feature a Blenheim bomber appearing overhead. Technically it's the wrong kind of Blenheim, a shortnose MkI instead of the correct longnose MkIV, but not many people will notice, and as it's the only flying Blenheim in the world they didn't have much choice. The Blenheims were over Dunkirk every day, 50 to 80 at a time, bombing the Germans on the perimeter to hold them back, and my uncle Lawrence, then serving with No.21 Squadron, was flying one of them. (He was killed in action leading the Blenheims of No.107 Squadron against a Bremen U-boat factory, at zero feet, in daylight, on 4 July 1941.)