Really, one of the best sci-fi films ever. Grant Williams' performance towers above an outstanding script by Richard Matheson and the supporting cast pulls out all the stops.
This is an intelligent film that leads you into the spiritual rather than the violent, no two ways, and I can't say enough good things about it. However, I read one review that complained about the lack of W/S presentation. To that, I can only say that for years I didn't even know that such a thing as W/S existed. This Full-Frame edition is the only way I know it and, as such...this is a piffling detail.
BTW, in the US you can get this as part of a dirt cheap package from Universal called "Sci-Fi Ultimate Collection" which features four other films from the 50's of sufficiently suspect quality to be well worth buying.