I've read this book in school, of course. I like it - It's about a Southern lawyer, Atticus Finch, who defends a black man who's been accused of raping a white woman. It's also a coming of age story for Atticus' daughter Scout, the narrator. It's one of the Great American Novels. The whole movie has a sort of lazy, heat of summer feel, and there's also a theme about having empathy for people, and not hurting innocent things. It's a classic.
Gregory Peck is really well-known for this role. I always thought that he didn't seem all that much like Atticus, apparently Harper Lee herself loved it, so I suppose I'm alone there. Something's that great to me about this movie is how much people love Atticus. The American Film Institute has a list of the greatest heros in American film, and Atticus is number one - Just ahead of James Bond and Indiana Jones. There's something terrific about that to me. Atticus isn't fighting Nazis or Communists, he's just a regular, stoic guy who's doing the right thing even though he can't win and it causes trouble for him. I love that that's the kind of guy people idolize.
I also want to point out that I've been to Monroeville, Alabama, which is the town that the town in the movie is based on, and that childhood friends Truman Capote and Harper Lee both have works that ended up on this list. Fun fact.