It's an amazing movie, he didn't deviate from the shows script, he just shrunk it added nothing new and sumarized the entire first season in 1 and a half hour.
What's sad is the show creators summarized the entire series (minus the ending) in a 20 min episode via the gang watching a play based on their lives.
Anyway after seeing the movie the sequel is out of the question, although they could go ahead with Book 2: Earth as M.Night Shayalamaan didn't screw up anything, he just didn't deliver any emotion or content.