Was the impact of the novel To Kill a Mockingbird positive or negative?

The impact of To Kill a Mockingbird was overwhelmingly positive. The book was a huge success, achieving both popular and critical acclaim. It was also awarded the prestigious Pulitzer Prize, which came as a huge surprise to the book's author, Harper Lee.
A number of critics and commentators hailed the work for laying bare the racism and prejudice at the heart of white Southern society. Although To Kill a Mockingbird is set in the 1930s, little had changed in the South by the time it was published in 1960, and so the book was seen as a contemporary social critique. This was thought an incredibly brave thing for a white Southerner to do. It was certainly rare, as most white Southerners wholeheartedly supported the system of racial prejudice that existed at that time.
The publication of To Kill a Mockingbird coincided with the growing rise of the Civil Rights movement, and many civil rights campaigners thought that the book greatly helped their cause, as it showed how it was possible for people—especially white Southerners—to rise above their prejudices and accept racial equality.