I first saw Lifeforce back in 1985. I thought it was a decent sci-fi/horror concept of alien vampires. I agree with many of the other reviewers who said the ideas or concept of the film was good. Other than that it was entertaining, not great, but entertaining. There are really two good reasons to see this movie. And they are Mathilda May's boobs. Hell, her whole naked body for that matter. Man is she hot. She has to be the best looking vampire/alien that has ever graced the screen. Like another reviewer said, she plays evil, seductive, vulnerable and serious very well and all while being naked. To say the least it couldn't have been easy for her to play the role naked throughout the whole film. Needless to say,I'm glad she did. I agree Railsback was miscast in this. Otherwise, the film is alright. If you need to see major boobage,then rent this and watch it with the guys.