The trailers have sure focused a lot on Harrison Ford. I hope they haven't changed the story too much and minimized Ender's role to feature Indiana Jones/Han Solo.
First I loved the book and and have read most of the sequels. I probably will see the film but I have to say the trailers indicate that the "surprise" ending of the book is not there in the film or they spoiled it with the trailers.
As it always has been one of my favorite books, I took our son to go see Ender's Game in the theater today with my dad and a friend. Considering the source material and the requirement to condense it into a 2 hour movie, I thought they did a pretty good job. They changed a few things but I think they did a good job of keeping the "heart" of the book on the screen. Our son is 10 and he loved it, very appropriate for this age group. Dad liked it, too, and he can be a picky sort. Recommended.