In my estimation To Kill a Mockingbird is a well-structured novel, paced nicely with brief episodes that have independent a beginning, middle and end of their own while also contributing to a larger development of action, character and theme.
The moral and moralizing do seem to fit the O'Connor criticism cited by vangoghfan above. (post #6)
After reading some of the work linked to in post #6, I would agree that the novel's aesthetic structure is certainly sound and also entertaining. Yet, I still have some reservations about the overt nature of the moral, the symbolic nature of the Atticus character (while acknowledging the value message he serves), and the convenient access the children seem to have to subtle emotional and intellectual truths that are not available to other characters in the novel.
I disagree with the view that this is, on the whole, a realistic novel. It is a moral tale concerned with real issues, expressing its moral quite directly and baldly and using its characters as vehicles of instruction. It's a good book and it draws in high quality influences, but it is not without its flaws.
Because it is so entertaining, it makes a natural selection for use in literature courses for high school students.
This novel, for any of its flaws, has such a powerful message about how we should treat each other. When Atticus tells the children that you can't judge unless you walked in someone else's shoes, it touches a cord in most readers -- especially young readers who are so caught up in a world of first impressions, stereotypes, cliques, competition, and even bullying. When that lesson is added to others in the novel: not to "kill mockingbirds," the definition of courage, the flaws in any justice system, the evil of racism, etc. it becomes a timeless book that captures so many truths.
I did some work on the book recently, trying to defend it against Flannery O'Connor's claim that it is merely a book for children. I tried to argue that the book is more subtly designed and complexly unified that O'Connor may have given it credit for being. If you like, you can read most of the essay (minus the first page) here:
By the way, I was surprised by how harshly many recent critics treat Atticus Finch. To some he seems very weak and shallow -- an opinion I do not share.
I love the book. When my students read it, they realize the true power of language. Until they read this book, they have been reading only for stories. Then they see how language can be used, with a story, and it changes the way they look at literature.
As a student To Kill A Mockingbird was one of my favorite books. I loved Harper Lee's ability to transport me from my 9th grade desk to the south. Her use of the character's dialects, mannerisims, and events allowed me to see a different side of American history.
As a teacher, it's one of my favorite books to teach. My students deal with stereotypes everyday, and the book nudges them to look beyond them. Class, race, education- all of the issues my students face when they pick their seat in the cafeteria are brought into play (at of course a larger scale) in the novel.
I like the part that is about Jem and Scout and their coming of age. I do not like the Tom Robinson part of the story. It seems like a very forced and stereotyped episode. It's just too idealized -- perfect white lawyer Atticus defending poor black man Tom against the nasty white Southerners. It just doesn't seem realistic in the way the coming of age aspect does.
You may have noticed from all of my answers on eNotes concerning To Kill a Mockingbird that it is one of my favorite novels. It is highly realistic, deals with several important themes important to the Deep South during the 1930s, is well-developed and beautifully written, and features one of the greatest characters in all of American literature--Atticus Finch. Author Harper Lee's decision to tell the story from the viewpoint of the young tomboy, Scout Finch (through both her youthful and adult perspective), was an inspired move, and the addition of occasionally humorous moments help to create a contrast to many of the more serious moments.