Just got back from this movie, and it's very good. Sci-fi/horror, but not a geeky sci-fi. Yes, there are aliens in it, but more along the lines of badness of the Alien movies. The subplots give it depth that many movies in this genre don't have. I haven't read the book, but this was well done. The only real downer was Morgan Freeman. Good actor, but I don't think he was suited for this role.