Who is the narrator, can she or he read minds, and, more importantly, can we trust her or him?
First Person (Central)
Mibs takes the reins in telling the story here and we definitely experience everything through her eyes, ears, and heart. This means we are as certain as Mibs is that her savvy is waking things up, and that our opinions of characters are more or less formed by Mibs—so when she says, "I'm not sure exactly what it was about Lill Kiteley, but I took to her right away" (16.1), we take to Lill too.
Luckily for us, even though Mibs is still rather young, she's pretty observant about people and the world around her. So even though we're getting the world through the eyes of a thirteen year old, there's still a lot of detail that Mibs gives us as readers about what's going on around.
This first person perspective isn't without its limits, though, and though we get to know Mibs quite well, our understanding of other things—like, say, savvies in general—is limited to what Mibs tells us. This means things like scumbling—or more specifically, how to scumble—largely remain a mystery as we read.
It's worth it to not have all the answers, though, because Mibs is an excellent person to spend the book with. She's bright and interesting, and her journey from kid to teenager is a fun and interesting one to accompany her on.