Ender's Game is the most cinematic of the lot, and even that has tricky tonal issues, which are not helped by casting the kids older.
I've wanted to see this as a movie ever since I read it about 25 years ago, so needless to say I'm excited about this. Nevertheless, I would be lying if I said i wasn't a bit worried too. While the story has a lot of stuff in it that would look great on a screen, much of what makes the story what it is takes place in Ender's mind and doesn't lend itself well to visual presentation. Seeing that the studio is aiming it at the teen demographic and wants to make it the next franchise like Twilight/Harry Potter/etc. only makes me more worried that they'll just emphasize the visually impressive stuff at the expense of the heart of the story. Card's statement about what to expect only deepens those fears.