My husband and I went to see Ender's Game last night. He said it was interesting. I liked it but didn't love it.
I wanted to love it because I loved the book when I first read it in the 1980s. I didn't remember it well, however, so I listened to the audio book last month. It was different from what I had remembered, and not as striking, but it was still a very good story.
I think the biggest change in the movie is the condensing of the story. The book starts when Ender is about 6; the main action is finished when he is 12, I think; and it finishes when he is a young adult. In the movie, he is about 12 years old throughout. No doubt this was a cinematic necessity.
I thought Asa Butterfield was OK as Ender, but neither he, nor his kid compatriots, really nailed it. And without that, the movie just can't fly.
The Los Angeles Times has a much longer and more positive review, replete with videos and all kinds of stuff, if you're interested.