Beyond the Chocolate War is one of the creepiest books I've ever read in the young adult "genre." It's fiction, of course, but just realistic enough to be truly scary. The control teachers can exercise over students and the long term effects of what that control can be, and the control of students over one another make up the plot of this book and do an amazing job of getting at human emotion.
I enjoyed The Chocolate War better, I think, partly because there were more activities taking place in the classroom. I think Corimer missed some opportunities in this sequel. Brother Leon is a character that can only be truly effective in his element: the classroom. The first novel did a great job of mixing in and out of classroom events and I think for a novel to take place in a school, some of it has to involve classrooms.
This book definitely needs to be read after the first. Though there is a small attempt to catch readers up to the action, lots of obscure references are only truly powerful with the knowledge that comes in the first book.
I'm ambivalent about Corimer's writing style...I think I need to read more to form my opinion. He's definitely not poetic in his prose, but he manages to take stock characters (the mean teacher, the school bully) and turn them into truly chilling individuals that are memorable and could earn themselves several more books.