Pride and Prejudice is written in Third Person Omniscient point of view with a focus on one character, that being Elizabeth, hence it is a Third Person Limited Omniscient point of view. The advantage of this perspective is that even though the narration focuses primarily on Elizabeth, the narration allows the reader to see other scenes and characters' thoughts and actions that we would not otherwise see if our narrator was not all knowing, all seeing. For instance, we are with Miss Bingley and Darcy strolling through the garden while Elizabeth is visiting Netherfield. Even though Elizabeth is not present, we get to hear Miss Bingley tease Darcy about the prospect of marrying Elizabeth. We are also with Charlotte when Mr. Collins asks her parents permission to marry, hence we know before Elizabeth does all of Charlotte's reasons for choosing to marry him. Being with other characters allows the reader to gain deeper insights we would not otherwise gain if we were only with Elizabeth the whole time.
Not only that, the Third Person Omniscient narration also allows Austen to employ her witty irony that she is so fond of and uses so well. In the case of Miss Bingley teasing Darcy, not only is this scene ironic because Darcy does actually marry Elizabeth, it also allows for foreshadowing. Furthermore, in instances where the characters' words come back to haunt them, such as Elizabeth's remarks on Darcy's pride, because of the omnipotent narration, we already have the impression that Elizabeth is wrong, so we can suspect that their is irony in Elizabeth's words.
Normally a disadvantage in Omniscient narration is that the reader does not get to become close with any characters because none of the narration is seen from the "I" perspective. However, Austen solves this issue by making it a Limited Omniscient narration, focusing on Elizabeth. Therefore, we are with Elizabeth throughout, hearing her thoughts and feelings, also hearing the narrator's words of wisdom, and get to empathize with Elizabeth when she finds out that she has been completely wrong.
All in all, there are only advantages to the Third Person Limited Omniscient point of view Austen chose, and no disadvantages.