I first read this book in middle school, and didn't get a lot of what it was saying. There were a lot of description scenes in the beginning. That was definitely a lot to digest. But after you're introduced to how the school looks (for the second time), then the rest went swell.
I like how the book talks about what "good" or "evil" even mean, at all, and if it's 100% accurate in every situation.
There were definitely a lot of sexist ideas and scenes in the book, as well. That's not cool. If you're going to have sexism, then I need an equally good rebuttal to call it out. There wasn't a lot of that. Good sass to bad makes things all the more enticing to read.
This book is about questioning what you want to be, and why you would like to be it, so bad. Why do you want to be good? What IS good? This is Sophie's dilemma.
On the other hand, Agatha struggles with the meaning of beauty. What IS beautiful?