Book Review: I Am Number Four

So I was super excited when "I am number Four" came out but waited until it was out on DVD to watch it. It was a really good movie with great special FX, a good story and the ending leaves you wanting more. I hope they make another follow up. I'm really into alien movies and superhero type of stories! (as I write this I'm thinking of watching it again since it's been awhile.)
But now I will talk about the book which in my opinion wasn't exactly up to par. I say this because I expect a lot when it comes to books. I started reading the book back in the summer, maybe June. I just finished it last week on Friday. Why it took me so long well because it wasn't as entertaining as I expected it to be. Some of the story was confusing and boring. Is it because it was two authors collaborating with each other and just didn't quiet work out in the end? Or because I watched the movie first and it affected my opinion of the book? I have no idea what it was but it has taken me forever to read this book and in the end it wasn't that great. I love the history of it, the powers and the new ideas they have brought in but the way it was executed wasn't the best.
I still struggled through it because it's one of the alien books I've been wanting to read for a while.
Yet I don't know if I'll read the next book "The Power of Six"
I probably will because I never leave a series unfinished.

Have you guys read this book? Or any alien/superhero books?