I think, it would have to be Ender's Game. Without revealing too much along the story, they missed so many key moments in Ender's "childhood" I ended up turning my TV off the first time I watched it. So what is your opinion?
-
The Hobbit. I loved the book but the movies SUCK. There is just too much irrelevant crap mixed in, and stretching it out into three movies shows Peter Jackson just wants money, which is really sad because the LOTR movies were good.