Part of that could be that I read this immediately after I read When You Reach Me, which shares many coincidences: both have 6th grade female protagonists with male best friends, experience bullying, and are receiving messages from an unknown source and struggle to piece together the mystery). There are more similarities I could list. So, I spent those first chapters comparing the books, which I am sure took away from 8 Keys.
Nevertheless, it was a pretty good read. I just preferred When You Reach Me instead - better writing, better character development, better suspenseful elements.