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.
I have the book but haven't read it yet. I had like 9 books to read this semester so I'll wait for the summer.
It also has an Animatrix short film, The Final Flight of Osiris before the movie, and it's pretty good. I'm not typically into horror, but this was pretty good. I might buy it when it comes to video.