Elizabeth listened in silence, but was not convinced; their [the Bingley Sisters] 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.

This feeling is reinforced several times.

In Ch 6. Elizabeth still saw superciliousness in their treatment of everybody, hardly excepting even her sister, and could not like them

Which leads to one of my favorite LOL lines:

Ch 8
The sisters, on hearing this, repeated three or four times how much they were grieved, how shocking it was to have a bad cold, and how excessively they disliked being ill themselves; and then thought no more of the matter; and their indifference towards Jane when not immediately before them, restored Elizabeth to the enjoyment of all her original dislike.

Elizabeth feelings correspond to author's comments:

Ch 4
They were in fact very fine ladies; not deficient in good-humour when they were pleased, nor in the power of being agreeable where they chose it, but proud and conceited. They were rather handsome, had been educated in one of the first private seminaries in town, had a fortune of twenty thousand pounds, were in the habit of spending more than they ought, and of associating with people of rank, and were therefore in every respect entitled to think well of themselves, and meanly of others.

The last of which caused me to make the notation "the original mean girls?" in the margins of my copy.

I must confess that I originally read "one of the first private seminaries" as 1st chronologically speaking and not as 1st in prestige (though I suppose the most prestigious could be also have been one of the first chronologically.)