Having not seen any other versions of the story nor read the book, I'm going into this interpretations with absolutely no idea about the true nature of the story, or perhaps how the tone should be. This as just a film though I felt worked as basically "proper" screwball romantic comedy. A great deal of a reason for this is Laurence Olivier as Mr. Darcy who we meet as one of the targets of the Bennet sisters' mother for a proper suitor for her daughters. Mr. Darcy though is not the sweeping romantic type though, and Olivier actually takes a similair approach to the character that Daniel Day-Lewis would later take with a somewhat similair role in A Room With A View. That being that Olivier goes about portraying Darcy as an excessively proper English Gentleman, particularly in the early scenes where he first meets the Bennets including Elizabeth (Greer Garson). He makes a poor initial impression by making his patrician attitudes known out loud, and Olivier depicts him as a man almost constrained within himself in his tight movements, and the fairly stilted voice he uses as though every words has been rehearsed over and over again beforehand.
Olivier, like Day-Lewis in that later film, does a great service to the film through his work as he makes Darcy quite an amusing presence in the film by making his proper behavior extreme enough that it actually becomes quite comic. The best part about this is that there is nothing that Darcy does that is necessarily funny in itself but Olivier effortlessly brings out through his purposefully overt performance. Although Olivier does technically over do it, so the character is funny rather than just serious and dour as I feel he easily could be, Olivier does not over do it to the point that Darcy is merely a caricature either. Rather Olivier is quite effective in fashioning the barrier necessary for the character, since there must be some transition for Elizabeth. Olivier interestingly is able to help realize this through his own performance as he depicts the surface of the man as almost impenetrable. Olivier does not do this in order to portray Darcy as cold or unfeeling, but rather fashions the reserve fitting for a man who has spent all his life learning to behave in this distinctly proper fashion even though it may not actually be the true nature of Darcy after all.
Although much of his performance is in the role of being a tad overstuffed, and entertainingly so, Olivier is terrific in alluding to the better nature of Darcy quite early on. The moments where she purposefully embarrasses him Olivier quietly depicts Darcy not reacting like a simple pompous fool being surprised, but rather a more complex man being honestly hurt by this treatment. My favorite scene of Olivier's has to be his initial proposition of marriage of Elizabeth that rejects as in the single scene it shows exactly what's so good about Olivier's performance. In his stumbling proposal Olivier is very funny as well as in his needlessly direct responses to Elizabeth when she announces her objections, as he always stays as the proper gentlemen who never should be too emotional. My favorite moment in the scene is as Darcy exits the room, and its only a brief moment though an extremely important one. When Darcy finally turns his head away from Elizabeth's view Olivier shows just how genuinely torn apart emotionally Darcy is by the rejection, and in the moment Olivier is quite moving by revealing the sensitive man he really is. Olivier is able to make Darcy transition from pompous charmless gentleman to the perfect rather charming gentleman a wholly effortless one, by creating the sense that Elizabeth brings this better side out of him. It's not a change exactly, but rather simply having him shed some of his thick shell he learned over the years. It's strong work from Olivier and I doubt I would have liked the film to the same degree if it were not for his performance, as much of the humor of the film comes from him. It's a splendid performance, that might not be his best work from 1940, but that's hardly a problem.