I remember seeing this movie when I was a kid and being blown away by it. Of course, that was forty years ago and special effects and so on have come a long way in the meantime, but nonetheless this was a great bit of cinematic nostalgia and—to me—something of a collection piece. Star Wars it ain't, but you wouldn't expect it to be, would you?
Yes it's hokey, yes the performances are hammy, yes it's predictable, yes the story is highly implausible (even for b-grade science fiction) but nonetheless it's a fun movie. Recommended.