What I most enjoyed was the subtly comic tone. When I really like a book, I tend to overquote on my blog. Here we go:
Maycomb was an old town, but it was a tired old town when I first knew it. In rainy weather the streets turned to red slop; grass grew on the sidewalks, the courthouse sagged in the square. Somehow, it was hotter then: a black dog suffered on a summer’s day; bony mules hitched to Hoover carts flicked flied in the sweltering shade of the live oaks on the square. Men’s stiff collars wilted by nine in the morning. Ladies bathed before noon, after their three-o’clock naps, and by night fall were like soft teacakes with frostings of sweat and sweet talcum
"You know she's not used to girls," said Jem, "leastways, not girls like you. She's trying to make you a lady. Can't you take up sewin' or somethin'?" "Hell no. She doesn't like me, that's all there is to it, and I don't care. It was her callin' Walter Cunningham trash that got me goin', Jem, not what she said about being a problem to Atticus. We got that all straight one time, I asked him if I was a problem and he said not much of one, at most one that he could always figure out, and not to worry my head a second about botherin' him.