I read the book Ender's Game more than 15 years ago. It immediately joined my top 25 most recommended books. The next few books are very skippable. I recommend giving copies to your middle school aged kids, particularly if the kids are smart. Gifted kids really relate to Ender and he can help them accept their brains more readily. It's also on the recommended reading lists for command staff in all branches of the military for the creative tactical thinking used by Ender.
Making the movie was a pain in the butt. The main enemy in the book is Ender's brother who spends most of the book on a different planet. And almost the whole cast is young children. They didn't think they could find enough children who were decent actors. Orson Scott Card tried using elements from "Ender's Shadow" which tells the same story through the eyes of another character. And after years of trying they finally managed to pull it off.
There are some issues. Some are memory issues since it's been so long since I read it. Most are due to time constraints. I don't remember Earth schools being as militant as they're presented in the movie. Mostly I would like to have seen more time in the battle arena. They don't really show how the battles work or get into the tactics that Ender came up with to make his team great. So when his team does finally fight you don't really understand how much things have been stacked against him and how much the commanders are cheating to screw things up for Ender. But the battle they showed did cover some of the features of book battles that I liked as well as mirroring the battle tactics that would be used at the end of the simulations.
I also want to talk about the science in the movie. They seemed to make an effort to avoid magical tech whenever possible. For the most part I believe that the world they presented could be real in 50 years if the political will was there to create it. The instantaneous communications system between star system is theoretically possible using quantum entanglement. With a few exceptions the space station's variably gravity was doable. It seemed to be based heavily on the ships and stations in "2001: A Space Odyssey". Only the big weapon at the end seems of questionable tech.
I liked this movie and recommend it, but I recommend reading the book, too. Any order you like is fine. Just take in both.