The decision to publish Harper Lee's early draft of To Kill a Mockingbird was a bad one. According to some reviews it's not particularly well written, aside from the very different portrayal of Atticus. It's unfortunate that Ms. Lee is too infirm to have had a more forceful say in the decision one way or the other.
On the other hand, if viewed as a historical evolution rather than a literary one --I'm sure academics will have a field day dissecting and comparing the two books -- had Ms. Lee sat down ten years ago and discussed the evolution of Atticus within the context of the changes in the civil rights movement, it could have been fascinating. Brown v Board of Education was in 1954, her first draft (Watchman) was submitted around 1957, and Mockingbird was finished in 1960. As my wife has pointed out, just look at how fast attitudes have changed in this country with regard to same-sex marriage. Certainly there's an analogy there to Lee's perception of racial attitudes and her portrayal of Atticus. Did that result in a more hopeful Mockingbird?
The New Republic had a very interesting series on the controversy at: