Just in case you're stupid, this will not be a post about the details in the I Am Number Four book that they forgot to mention in the movie (though I could gladly do that for you). This is about which is better: I Am Number Four the movie or the book?
Those folks who aren't serial readers think that every movie is better than the original book. We readers, beg to differ.
I saw IAN4 before I read the book. When I saw the movie, it instantly became my favorite. I thought that it was the most awesome thing. The music was great, the dialogue was great, and the abs on the main character were indeed great.
When I read the book, I absolutely loved it. Books foster something movies can't have. It plainly tells you the body language and foreshadowing the author wants you to pick up on. So I loved the book, too.
Needless to say, I watch IAN4 once more after reading the book. I could not stop laughing. The movie was nothing compared to the book. Some scenes were just downright stupid, like when the Mogadorians feed turkeys to their mutant pets? That was just so...dumb. I think that was when I turned the film off.
So I have to say, the book beats the movie, fair and square. Try for yourself. Read the book, than see the movie. It will amaze you. Now not all books are better than movies, but in this case, the movie didn't have a fighting chance.