A better editor would improve this book, which, as a superhero book, has a lot of appeal to an upper elementary audience.
There is much here to appeal to kids; in fact, my nine-year-old daughter who is entering fourth grade whipped through the first two books in the series. I like to know what she's reading, so I read some of the books, too.
POTENTIAL SPOILERS, AS A BIT OF TEXT IS QUOTED:
You'll find violence as well as threats of violence:
p. 49 "If you're captured by Skelton, they'll kill you. If you're captured by Dhoom, you'll beg them to kill you. Is that clear?" That's not an editing issue, but I think the story would be fine with milder violence (but that's just me; my daughter didn't object).
There are too many exclamation points (fewer in this book, book two, than in book one, thankfully), and there are some other errors that make a reader cringe, like this (not the only instance in the book) on page 156: "Or, is it somehow still inside of me, gathering it's [sic] strength? Even though I can't sense it's [sic] presence, can I ever be entirely sure it's gone?"
Each chapter begins with the profile of a Meta, which is fun - a bit of comic book to go with the superheroes.
Kids will like it, but as an adult, I hope some rough bits get worked out during the editing process!