Simply put, this is one of the greatest SF Films ever created. From beginning to end it is intelligent, exciting, thought provoking and has for the time, excellent SFX. The cast, led by Michael Rennie (in what is his best performance) is simply superb. This movie also boasts one of the most interesting (and for the time) amazing storylines ever. At a time when Aliens were thought to be BEM's and wanted only to invade and grab earths women, here was an alien giving us a choice; be as violent as we wanted to one another, but leave our violence here on earth - or else. Simply a great movie. I'm very disappointed that it's not out on DVD yet.