A few thoughts: This movie had me, it really did. I was totally invested and tense, awaiting a thrilling climax until...dammit. This is three-quarters of a really, really good horror thriller, but it sadly (and almost aggressively) dispenses of everything it was building up to in favor of an ending that makes very little sense when looked at closely, and betrays the entire previous hour of the film. That being said, it is still a solid movie with cool cinematography, minimal sets, and a great lead performance by Richard Boone who almost singlehandedly makes the movie work. The fairly simple set-up alows for the performance and character development to take central stage, which helps set this apart from the bigger, more fancy and exciting horror movies of its time. As long as you go into this movie knowing the ending will be a letdown, I could see most fans of '50s horror enjoying it. It's definitely a few steps ahead of a majority of b-movies of the time.
Who would I recommend it to? I repeat, fans of '50s horror should enjoy it. Not great thanks to the ending, but still worth looking out for.