This has some of the best aerial fight scenes ever - 'Top Gun' nothwithstanding. If it has faults it is that it can sometimes be a bit dull as it is very historically accurate, as it was a very well documented battle and presumably because when it was made many of the participants were still alive (and some still are).
It might have been better if like the 'Dam Busters' it had adopted a rather more documentary style, rather than having ground based ficticious sub-plots.
There are no particular stars (save the aircraft) but many cameos and it is even handed to the Germans as well, who lost many brave men.
The bits I liked were, as one other has commented, British diplomat Ralph Richardson telling German Curt Jurgens (over tea of course) that we wouldn't be dictated to and the scene in the RAF command bunker as one of the biggest daily air battles develops, where Churchill (suggested only by a puffing cigar but very much a hands on war leader), on surveying the plotting board showing hundreds of attacking German aircraft, orders more reserves into the battle only to be told there are none left, everything we had was in the air or on the ground being refuelled.
If the technology looks dated now, we must not forget that at the time radar was ultra secret and definitely cutting edge - this was the start of electronic warfare.
I believe I am correct in saying the film opened on 15th September 1969, celebrated in the UK as Battle of Britain day and the actual anniversary of the Churchill incident above.
This was truly the finest hour of those young pilots and we did it all without American help or even a Yank guest star..........
PS Christopher Plummer is Canadian!