The most prevalent tones throughout this story are the artful combination of ironic humor, acceptance, and childlike honesty. It is clear that the author is not intending to make a social comment at all, on the issues presented (such as poverty, neglect, mental illness, public schools, etc). I think it is more apparent that she wishes to simply tell the story of her life, as a child, from an adult perspective. But because her story happens to be one of poverty as well potential neglect and abuse, instead of passing judgment on her parents, or faulting them, she presents them simply as she knew them as a child. Hers was a unified family who loved one another, through everything, and still does to this day.
As a direct result of such a combination of tones, Walls manages to allow her readers to personally experience such "social issues" in the way she experienced them, and the reaction, judgment, and response is therefore left entirely up to the reader. One of the reasons this book is so intriguing to me was the lack of forced emotion and, dare I say, lack of bias. It truly reads as honestly as if a child were telling it. However, because that child has grown up, some of the humor presents itself in that ironic chasm between childhood innocence and adulthood knowingness. Walls takes a very personal experience, and rather than extorting herself or her family and rather than getting on a political or social soapbox, she simply becomes transparent.
The reader doesn't leave with a feeling of pity for Walls' situation (or poverty in general) because the author does not present self-pity. The reader doesn't walk away with anger or resentment toward Walls' parents, because the author seems to hold none herself. If nothing else, it is easy to agree with the author that she has overcome a great hardship, but just as easy not to make her into something that is larger than life because of it.