I got the DVD of the film and did enjoy it a lot.
However there was one thing I found irritating. Some of the music. It was like at ticking noise, very similar I thought to the attack scene in Pearl Harbour. I think it was to make it suspense, but it actually got annoying at times.
The only other strange thing, which generally doesn't happen on DVD, is that film was shot on 2.35 Cinemascope, where you would normal get two black bars on a standard widescreen TV. But for some reason it goes to full screen on the standard TV and only at the end for the titles does the two bars appear
Perhaps the Blu-Ray has the proper screen size, so you might want to consider getting that. Especially as the film was shot with Imax cameras.
The DVD does come with an extra features disc, which explains how they made the film. What surprised me, because what I was expecting to hear was it was all done with CGI. And it WASN'T.
Thousands of men extras, real Spitfires, real ships and they even recreated the dock actually in Dunkirk, building a full sized structure. Most of the beaches too were at Dunkirk. Even the small boats were the original craft used to take the real soldiers over. Except Moonshine, but it was built by the company that did make boats and it was of that age.
They even created a special plane that looked like a Spitfire, but had a back seat pilot in it. Just so the could film the actor flying in a plane!
One of the crew pointed out that no real Spitfires were damaged or destroyed in the film
The only thing that was lacking was how they did the Stukas. Since none have actually survived, or at least none that can fly. That I know of anyway. The Battle of Britain had that problem in 1968. So they built large scale Radio Controlled models.