Also known as the Citizen Kane effect: you hear about how amazing and ground-breaking the film was, and then you watch it and it feels vaguely disappointing.

Then you go watch a bunch of other films from 1939 and come back and watch Kane again, and this time you're blown away by it, because you're seeing it in its own context and not your later one, and you can see how different it was from everything else before its ideas were co-opted by later films.

(At least, this is how it generally works out for me...)