Sci-fi movies differ a lot from sci-fi books. So much more data can be put into a book, than in a movie. Sci-fi movies are there to please the audience, and most audiences don't want to be swamped with complex scientific anology which you need to understand just to comprehend the plot. Movies are more about making money.
I must admit I love the Matrix and its sequel, a lot of people who know me just roll their eyes when I start talking about it, I just love the movie.
So what is your favourite sci-fi movie?