Narrated in part by Rod Serling, this early 70's film is actually a lot of fun if you're into the feel and low-key style of 70's horror. No gore, no nudity, no jump scares, just three moderately spooky tales that are varying degrees of entertaining.
Of the three stories, only the final one is a bit closer to average, in part because much of it are flashbacks of a tragic love story, complete with a three-minute montage of the two love-birds frolicking in the fields, running hand-in-hand, to a slow 70's love song. I'll be honest, the third story, which is a rendition of the vanishing hitchhiker legend, can be boring, and you see the ending come long before it gets there, but it has its charm.
The first two stories are damn good, though, and though I utterly loved the first one and it's moderately complex plot-layering, the second's ominous feel and inconclusive conclusion really made it one that stood out. A low ground-fog, unearthly howls emitting from a hole in a field, townsfolk trying to decide what to do, it was a lot of fun, again, in that low-budget, low-key way.
I'm hard-pressed to name anyone who did an out-of-the-world job, though it was nice to hear Serling narrate the beginning and end of each story (book-ending the movie as a whole was a different, uncredited narrator). Really, everyone did pretty well in all of the stories, and no sore thumbs stick out. Acting wasn't the high point of the film, but everyone pretty much handled themselves competently.
The main problem, aside from the issues I had with the final story, is that the final ten minutes of this movie is simply a lesson on the unknown - history of witchcraft, for instance, and questions of coincidence versus supernatural causes, and just a lot of rambling. It showed clips of the previous stories while a narrator (not Serling) just kept talking and talking, again, for ten minutes. This easily could have been removed, leaving the movie at eighty minutes, and I think it would have felt just a bit more fresh.
If you love 70's horror, and are okay with slowing things down a bit, Encounter with the Unknown might be what you're looking for, because it certainly worked for me. 7.5/10 (rounded down to 7/10 to fit site's format).