Jane Austen actually does not give very many descriptions for her characters. She prefers far more subtle characterization techniques, such as dialogue.
However, one character that is described is Elizabeth. We learn in the first chapter that her father believes she is more intelligent than her other sisters. We learn at the Meryton ball that she has a "lively, playful disposition, which delighted in any thing ridiculous" (Ch. 3, Vol. 1). Concerning her looks, we know that Mr. Darcy thinks her "dark eyes" possess a "beautiful expression" (Ch. 6, Vol. 1). We also know that he thinks her figure is not perfectly symmetrical, but that it is "light and pleasing" (Ch. 6, Vol. 1). Elizabeth is also acknowledged as the second most beautiful Bennet daughter next to Jane (Ch. 15, Vol. 1).
Jane is acknowledged to be the most beautiful daughter (Ch. 1, Vol. 1). She is also described as having a very naive and trusting character. She is very quick to accept everyone as wonderful and dismiss their faults (Ch. 4, Vol. 1).
Mr. Bennet is described as being intelligent, having a "sarcastic humour," "reserved nature," and also as having "caprice," or an unpredictable nature (Ch. 1, Vol. 1).
Mrs. Bennet is described as understanding little, knowing little, having an "uncertain temper." She also always "fancied herself nervous" (Ch. 1, Vol. 1).
Mr. Darcy is described as very tall and handsome, but also as very proud (Ch. 3, Vol. 1).
Austen also feels that Mr. Collins merited physical description. He is described as being tall, but also very "heavy," meaning obese (Ch. 13, Vol. 1).
Another character's description that is worth mentioning is Charlotte Lucas's. She is described as being plain and already 27, two reasons why she accepted the proposal of Mr. Collins (Ch. 22, Vol. 1). She is also described as being "sensible" and "intelligent" (Ch. 5, Vol. 1).
A complete index of all the characters in Pride and Prejudice and their descriptions can be found in the link below.