The concept for this book is awesome. As a first-person narrative, John Smith, aka Number Four, is a fugitive on Earth because his home planet, Lorien, was destroyed by another planet's race of Mogadorians. He seems a little discouraged and defeated in the beginning of the book because it's just a day in the life of always moving, travelling, making no friends. The only company he has is his Cepan, or guardian, Henri. Their relationship seems very genuine and loving, like a father and son (even though they are not related), which I loved. John remembers little from his home planet, and wants to create a life for himself on Earth. When Number Three is killed, Henri and John move to a small town in Ohio, Paradise. There John meets the love interest, Sarah Hart, and his new friend, Sam, and tries to come to terms with his powers and his future on Earth. 
 I loved Sam, in the book and in the movie. He was also stuck in a state of being discouraged and defeated, by bullying and by the disappearance of his father, until he meets John, who inspires courage and hope in his new pal. He's a loyal friend who happens to have an obsession with the extra-terrestrial. Duh duh duuuun. 
 Sarah Hart...how do I put this? She's nice...way too nice. She honestly has no personality for me except that she likes photography and saving homeless animals. I was kind of sick of their romance halfway through the book. Too cutesy and shallow for me. I'm good with a book with very little romance, and for me, I Am Number Four could have done without it, or had a better female lead who wasn't a total airhead. Dianna Agron played a much better (and snarkier) Sarah in the movie. 
 The action parts were my favourite, especially with John learning how to use his Legacies, or special abilities, that some of the people on Lorien are born with. The movie messes up his powers (boo), and actually forgets one altogether, which is too bad, because it's my favourite. There's an epic battle scene at the end, and the suspense practically kills you beforehand because everything is amped up as John struggles emotionally and physically to stay in Paradise.