Elizabeth is interested in sketching others' characters. For example, she observes the Binglettes early on and forms a judgment about them:

Elizabeth listened in silence, but was not convinced; their behaviour at the assembly had not been calculated to please in general; and with more quickness of observation and less pliancy of temper than her sister, and with a judgment too unassailed by any attention to herself, she was very little disposed to approve them. (chpt 4)
...
their indifference towards Jane when not immediately before them, restored Elizabeth to the enjoyment of all her original dislike. (chpt 8)

And we later have this judgment of Miss Bingley from Elizabeth:
Miss Bingley, I am sure, cannot. She is not such a simpleton. Could she have seen half as much love in Mr. Darcy for herself, she would have ordered her wedding-clothes. (chpt 21).

The passage as for Mr. Hurst, by whom Elizabeth sat, he was an indolent man, who lived only to eat, drink, and play at cards; who, when he found her prefer a plain dish to a ragout, had nothing to say to her later on in the same chapter also implies some judgment by Elizabeth of Mr Hurst.

Elizabeth also at some stage clearly forms views on Mr Collins' character:My dear Jane, Mr. Collins is a conceited, pompous, narrow-minded, silly man: (chpt 24). I'm inclined to think that she forms that view at the same time Mr Bennet does, when listening to Mr Collins during the first day of his visit to Longbourne, but I don't have any textual evidence that specifies this.