I loved finding out that several publishers turned the book down because they thought it too odd, too difficult for children, and too genre bending. It is odd, it is difficult, it does bend genres - and that's part of why I love it.
I didn't know the 50th anniversary was coming up, but we coincidentally just listened to Wrinkle as our in-the-car family audiobook. When we are listening to audiobooks, the kids will ask me to pause it if they have questions about what is going on or what a word means. Wrinkle did lead to many pausings - but what rich conversations we had. What is a tesseract? What is two-dimensional? What is evil?
It's a challenging book, perfect to expand young minds. It's also a fun and engaging adventure, and all about love and family and self-acceptance, not just math and time travel and good versus evil theology.