This is a docudrama that requires both an interest and prior detailed knowledge regarding this historic event. As a Strategic Planner by trade, I found the logistical actions primarily directed by Royal Navy staff officer, Captain Tennant, who on May 26th was dispatched on board the destroyer HMS Wolfhound to Dunkirk to aid in the evacuation of more than 330,000 British and French troops left stranded when France fell to the Nazis, [official account] fascinating. My wife found it sad, upsetting, and tragic. Not something that everyone will appreciate.
Knowing the story and admiring the logisticians and their exceptional execution of a famous, and "glorious defeat", and my appreciation of the minimization of what could have been a grander victory for Germany and a more severe defeat for the English is something that one needs to know as much about beforehand or risk feeling disconnected with while viewing.
There is also a bit of fictionalization of events that may have occurred to some specific B.E.F. members, but isn't the actual focus of what happened in reality, and may be distracting. Overall, a film I have seen at least 8 times, by choice, though as I said, others might find it lacking connection or continuity unless this type of film is to their liking. This is actually a segment from a multipart BBC series called "BBC History of WW2", which covers numerous theaters akin to "The World At War", but less of a documentary and more of a story.