The book begins following Bean as a orphan living on the streets of Rotterdam, and without giving away too much of the story, has his genius recognized by a nun and whisked away to Battle School. One of my favorite realizations that becomes apparent in the book is the fact that intellectually, Bean surpasses Ender. The fact that, knowing this, Ender is still chosen over Bean to lead earth's forces against the alien enemy. This is just one example of the deeper themes in the book - that Ender's humanity (which Bean struggles to find within himself) is the greater factor that endears Ender's jeesh to him.
One of the things that really attached me to this book is the masterful way in which Card takes seemingly insignificant details, events, and circumstances from Ender's Game and unravels an intricate story and explanation to these - from the composition of Dragon Army to how much more Ender's appreciation of Petra and Bean after the final battle means once you see their full contribution through Bean's perspective. And finally, the subsequent books following Bean, Petra, and the rest of the jeesh are much more engaging than those that follow Ender.
I hope that the Ender's Game movie introduces people to the book Ender's Game, but I hope that it doesn't end there. Hopefully the movie and all the attention it will surely garner will not only introduce people to the book, but to the rest of the Enderverse. The depth of the world which Card weaves goes so far beyond Battle School and the Bugger Wars, and to fail discover that world would be to miss the larger mass under the visible iceberg of Ender's Game