Though thick, this book is a fast read due to generous sections of comic art and a large, readable text. I'd say my almost third-grade son could read this, if he had a mind to, though it's rather on the long end for him. However, it's broken into short chapters. I think the book might lend itself better to a slightly older age though. I'm really bad at judging but I'd lean towards 5th-7th?
The comic sections are used to portray his inner thoughts, which is fun and effective.
This book tells the story of an inner city boy in a less than fantastic part of town, brought up by his grandmother, and going to school at a disadvantaged school. As a white woman reading it, and knowing it's written by a white man, I feel that it feels kind of like a scrubbed clean experience, but still doing a good effort to try and portray some of the thoughts and experiences of kids with those problems, while still trying to keep content appropriate for a very young audience.
It encourages introspection on bullying and fighting for things you believe in. It has some "don't judge a book by it's cover" moments about other kids in school. It has moments where the protagonist gets pulled into new experiences where he does wrong things, and encourages ways to solve problems, stand up for oneself, and set things right. It doesn't say that things will always be perfect if you protest and stand up for yourself, but encourages it in a realistic way.
Though it's not a perfect book (the pacing felt both good, but somehow a smidge stilted?), I think it's got a lot going for it for young audiences.