Final answer:
The quick opinion formed about Darcy's character is that he is proud and aloof, which is established early in the novel and is central to its themes.
Step-by-step explanation:
The opinion concerning Darcy's character that is quickly established in Jane Austen's Pride and Prejudice is that he is proud and aloof. In the early interactions with the Bennet family and the people of Meryton, Darcy comes across as haughty and disdainful, which contributes to the initial negative opinion formed by Elizabeth Bennet and others in the community. As we see later in the story, this opinion is challenged and evolves as the true nature of Darcy's character is revealed, representing one of the core dynamics in Austen's exploration of themes of pride, prejudice, and social perception.