Having made a life-changing mistake in marrying his wife, Mr. Bennet is now a sarcastic and generally distant father and husband.
Pride and Prejudice is about nothing if it isn't about consequences. What do we mean? Well, think about the way romantic comedies work nowadays. Two people meet in a cute way, get separated by nonsense, and then in the end are reunited at last. It's a little bit like fairy tales, with the "happily ever after" implied and never really shown. In Austen, though, we actually get to see what the upshot of the "ever after" is, with the pretty clear sense that some "ever afters" are way better than others.
With all of that in mind, let's flash back to what Mr. and Mrs. Bennet's whole romance must have been like. A beautiful, fun-loving girl from a middle-class family meets a funny guy on the lower end of the gentry totem pole. They are really attracted to each other, and bam! Whirlwind courtship ends in a nice wedding ceremony.
Sounds perfect, right? Well, as it turns out, the genius of the novel is showing us just what that initial attraction turns into after 22 years. It turns out that picking your wife based just on appearance and sexual chemistry isn't such a great idea. In fact, the repercussions are pretty dire, as Mr. Bennet basically just washes his hands not only of his wife, but of his whole family. He mocks them and comments obnoxiously on their lives, but his disrespect and dislike of his wife has basically translated itself onto his children as well.
Still, though not a great husband or a really responsible dad, we think he's hysterical. Mr. Bennet is sarcastic, witty, and insightful. The man is frequently a bemused spectator in the midst of unpleasant situations – namely, his marriage – but he always has some pithy comment or observation to voice. Elizabeth inherits both his sense of humor and his ability to make light of awful situations.
Fortunately, Elizabeth failed to inherit his less desirable qualities: poor judgment and laziness come to mind. We don't care how much Lydia begged and pestered – it was a bad decision to let her go to Brighton. And seriously, not saving money for his daughters' futures? Poor judgment call and laziness. Rather than take an active role in his family life, Mr. Bennet prefers to hide out in his library and dodge responsibility.
OK, pause. We have to try and make one last stand in defense of Mr. Bennet. Though he can be pretty obnoxious with his younger daughters, he does care for Elizabeth. He warns Elizabeth against marrying someone she doesn't care for or respect. Guess he doesn't want his daughter to repeat his big mistake.