I've read this book twice. When I read this as a kid, I got very confused once Meg and everyone is inside Charles Wallace's body, but I don't remember much else of my reaction.
Upon reading this as an adult, I enjoyed the book, but it wasn't all that this series was hailed to be. Out of the four books ([b:A Wrinkle in Time|18131|A Wrinkle in Time (Time, #1)|Madeleine L'Engle|http://photo.goodreads.com/books/1202853583s/18131.jpg|948387], [b:A Swiftly Tilting Planet|77276|A Swiftly Tilting Planet (Time, #3)|Madeleine L'Engle|http://photo.goodreads.com/books/1170900040s/77276.jpg|1196024], [b:Many Waters|151370|Many Waters (Time, #4)|Madeleine L'Engle|http://ecx.images-amazon.com/images/I/518agSAfzXL._SL75_.jpg|1575861], and [b:A Wind in the Door|18130|A Wind in the Door (Time, #2)|Madeleine L'Engle|http://photo.goodreads.com/books/1219188637s/18130.jpg|1196035]), Many Waters is quite the best, and A Wind in the Door is the one I would least recommend.