No, we don't mean that it's full of seventh grade-style spelling errors or that it's written on (shudder) binder paper. Kinkaid is a master of characterization, and she manages to write, stylistically, in the manner of an adolescent's thought processes.
We're sure that in those first weird years of puberty you felt insane swings of emotion. One day you were up, up, up and the next you felt as if your heart had been run over by a steamroller. Kinkaid knows how that feels, and so does her creation Annie John:
When my eyes rested on my father, I didn't think very much of the way he looked. But when my eyes rested on my mother, I found her beautiful. Her head looked as if it should be on a sixpence. What a beautiful long neck, and long plaited hair, which she pinned up around the crown of her head because when her hair hung down it made her too hot. Her mouth, moving up and down as she ate and talked at the same time, was such a beautiful mouth I could have looked at it forever if I had to and not mind. (2.8)
Holy emotional incontinence, Batman! Mom isn't just beautiful, she's omgthemostbeauteouscreatureeverilovehersomuchithurts. And when the tables turn, poor Annie is crushed. She doesn't stray away from extremes in pain, either:
I immediately said how much I loved this piece of cloth and how nice I thought it would look on both of us, but my mother replied, "Oh, no. You are getting too old for that. It's time you had your own clothes. You just cannot go around the rest of your life looking like a little me." To say that I felt the earth swept away form under me would not be going too far. (2.14)
Yeah, "to say that I felt the earth swept away form under me would not be going too far" is, actually, going too far. The earth did not sweep out from under you, Annie. You just felt bereft.
But dang if we the reader don't feel every uptick and downswing of Annie John's emotional journey. That's because Kinkaid keeps us fully in the mind (and heart) of an adolescent Annie John. It's an exhausting place to be… but it's never dull.