As I've written before, I haven't seen the Movie yet, but the trailer looked only as "Good" CGI-wise as the airplane scenes in Pear Harbour. I hope the true Movie experience is better.The cgi in the movie is dreadful. Its years out of date and totally detracts from the film. Many on imdb say the same thing.
Meanwhile, "Dunkirk" is magnificently believable - yes, I know, not so many planes & massive Warships in a scene, but it absolutely sold itself as "real" in my opinion.