We get our story from Mattie's perspective, and while we get a ton of insight into Mattie's mind, dreams, and emotions (which is good), we have to really pay attention to the text to figure out the other characters (which is a little more difficult). But that's the nature of first person narration; it sacrifices a wide perspective of the novel in favor of an in-depth look at one character in the novel. For more on this, be sure to check out Mattie's analysis in the "Characters" section.
In the case of Mattie, we think first person narration is the way to go. We get to see Mattie's innermost thoughts: how much she both hates and loves working the farm, how she resents the role she's been forced into, and what she thinks of, well, everything. More than that, we watch her question the validity of social expectations in her thoughts, which is great, because when she does voice her opinion in words, people tend to shut her down. Check it out:
He stopped dead in his tracks. "What on earth you want to do that for?" he asked, frowning.
"To learn, Royal. To read books and see if maybe I can write one myself someday."
"Don't know why you'd want to do that."
"Because I do," I said, annoyed by his reaction. (13.xerophilous.29-32)
Royal's lack of interest doesn't surprise us at all. But even her own sister Lou, who is so bent on bending as many social norms as possible, admonishes Mattie for some pretty radical thoughts. After Mattie expresses some of her beef with literature, the following ensues:
No one spoke for a few seconds. I could hear the clock ticking and the sound of my own breathing. Then Lou quietly said, "Cripes, Mattie. You oughtn't to talk like that." (22.glean.80)
So Mattie has learned to keep her counsel, which is kind of sad, because we think that others would benefit from her thoughts. But because of first person narration, at least we get to hear them as readers.
Did we mention yet that you should be sure to read up on Mattie in the "Characters" section for more about her as our narrator? Okay, we know we did. But we're saying it again since we really mean it.