I read the book a few years back as an adult and thought it was brilliant. I saw the movie by my lonesome, though, for reasons I will get into below. This will be mostly spoiler-free. I will make note of significant spoilers with plenty of warning and hope others will, too. I will not ask for a spoiler-free discussion, just give warning.
Overall Review
Mediocre as a movie and as adaptation from novel. Don't go out of your way to see it, but no need to run screaming if a buddy loads it up...like you really ought to if he loads up, say, Liquid Sky or Encounter at Raven's Gate.
Story Background
The book and movie agree on the background: Earth was attacked and nearly destroyed by aliens. Since surviving the attacks, Earth has engaged in an effort to recruit the absolute best possible fighters and leaders from as early an age as possible. The Earth military figured that young minds had a better chance of learning fast and being flexible enough to counter a truly alien threat. At the beginning of the book, Ender is 6YO and at the end, he is roughly 15YO. He works his way through the various filters set up to catch the less-able and eventually makes it to the top of the selection process.
Book Peculiarities
The book, as I wrote above, is brilliant. Really some of the best scifi written in the last century. If you have not read it, I urge you to do so. I have read only EG, not any of the follow-on books. From reading about them, I figured I would find them disappointing. This is not the majority view, however. I know what I like and don't and no longer feel compelled to force my way through a series with grim determination if I realize I may not cotton to subsequent efforts. Life is too short to drink cheap beer.
Movie Peculiarities
Relative to the book, the movie is shallow stuff. Even on its own, it was mid-grade Star Trek Movie quality and nothing to get excited about. Some of this is inevitable, some a failure of execution, but some was deliberate. The most egregious is that they blew the ending, robbing it of its power almost completely. It was a conscious decision to kill the profound and replace it with fluff & utter. Sad.
Material
I saw it without the kiddos as I felt the book material too much for children my kids' ages (7 & 9). It is PG-13 and if the movie had the same level of tension and had the disturbing emotional punch of the book, it is better geared toward the 15YO+ crowd. Note, I am not so fussy when it comes to fantasy violence in general. My kids understand that is fiction and I have allowed them to see PG-13 films. It is the more mature themes in Ender's Game that I thought too much for their unfiltered consumption.
In the end, the movie pulls most of the punches. One of them being the age of the actors and the movie time span. The actors look intended to be in the 15YO+/- age range, while the book starts when Ender is 5/6 and ends when he is age 15 or so. And the movie seems to occur in months, not years.
SPOILER ALERT
I suspect most any discussion / response will be spolierific.
