Even though this movie was made in 1964, it puts to shame the more recent (and astronomically more expensive) "Mission to Mars" and "Red Planet".
The characters act much more like real people/enslaved extraterrestrials than was common in sci-fi films of that era. Mantee is well-trained and resourceful, handling most problems (with the exception of his forced isolation) with reasonable aplomb. He is much closer to what we expect an astronaut to be than the ridiculous characters from MtM and RP.
The equipment is also a notch above the usual 60s fare, with real cables, actual dials and knobs, and that utilitarian look so common in military hardware. I have to give this film and extra half-star just for the realistic technology.
Overall, a good, solid sci-fi film from the golden age. Like many others, I'm waiting for the DVD.
*** out of *****