To my knowledge, there are no lengthy descriptions of the Bennett estate which is called "Longbourn." However, we may assume that the Bennets are at the lower-end of upper class. They still move in elite social circles; the house and grounds are groomed but not elaborate.
The Bennet's status in life is described in Volume 1, Ch VII:
Mr. Bennet's property consisted almost entirely in an estate of two thousand a year, which, unfortunately for his daughters, was entailed, in default of heirs male, on a distant relation; and their mother's fortune, though ample for her situation in life, could but ill supply the deficiency of his. Her father had been an attorney in Meryton, and had left her four thousand pounds.