There are actually many things that I dislike about the 1940 Pride and Prejudice adaptation, but the final resolution of Darcy and Elizabeth's courtship is one of the things that really, really bugs me about it. Basically, instead of following the novel (and I admit to being a purist when it comes to novel adaptations) the screenwriter threw out everything after Lady Catherine pays her unexpected visit on Elizabeth. Instead of Lady Catherine leaving Longbourn in high dudgeon, she pauses and tells her waiting nephew that Elizabeth is in love with him and essentially gives her blessing to the match.
My problems with this are:
It completely negates Darcy's sacrifice in marrying Elizabeth
It turns Darcy from a manly man who is willing to take an emotional risk in proposing to a woman who previously refused him into a weak child who uses his aunt in a complicated scheme of "ask her if she likes me"
I kind of like Lady Catherine the way she is in the book
On the sacrifice note, yes it is nice to think that everything will work out wonderfully for Darcy and Elizabeth but that isn't the story. The story is about two people who overcome obstacles in the course of finding true love and who have to make difficult choices and live with consequences. One of Darcy's consequences is an estrangement from his aunt, personally I think that Darcy does love his aunt and probably was not happy to be estranged from her, but he loved Elizabeth more and as a husband he could not tolerate Lady Catherine's abuse of his wife. It is an example of Elizabeth's maturity that she persuades her husband to mend the breach even though she was the one who was insulted and is the one with less affection for Lady Catherine.
On the second point, I'm just not in favor of something that turns Darcy into a wimp, especially a wimp who hides behind his aunt and lets said aunt be mean to the woman he loves so he can find out if she might like him back. That whole thing is just not cool. Darcy is a grown-up man, he may not be perfect and he may not be able to read Elizabeth's mind and he might have been spurred into action by hearing about his beloved's response to his aunt's interference, but he did not ask his aunt to interfere or come up with any sort of plan that involved his aunt interfering. I personally believe that had his aunt not interfered, he and Elizabeth would have still gotten together eventually, it just would have taken longer.
Finally, yes I do like Lady Catherine's character as described in the book. I personally think that we need to remember that she is seen from Elizabeth's point of view and introduced at a time when Elizabeth is prone to think poorly of all of Darcy's relations. The woman certainly has her faults, but I also see the possibility that she also has some good points that Elizabeth has chosen to overlook or misconstrue.