I have to say this is one of the books that made me think more than many I have read. First I saw the movie and I liked it a lot, but then read the book and I was amazed. Of course a book is always going to be richer than its adaptation, but sometimes it's movie can reflect all the philosophy of a book as 'The sorcerer's stone' but this was not the case. I belive the script is not up to par in a matter of meaning or main message than book. The movie transmits a different taste that make wonder if Orsson Scott Card (The author) was really satisfied with the adaptation. I gave it 7 stars because it has a great message (even if it's not really completed) and because I felt more dramatic the plot twist at the end of the movie than at the end of the book.
Wich, you have to know, it explains more of wat happen after Ender founs the Egg.