I've seen me a lot of bad movies, and I've seen me a lot of low budget movies.
Note: those two are NOT necessarily the same! I shouldn't even have to say this, but everyone who has watched at least a few movies (and that includes almost everyone in the United States), has had this experience; you go to a theater or turn on a movie channel. Sometimes you get a huge budget major studio film that is oddly hollow, perfunctory and disappointing. Sometimes you get a film that is entertaining in spite of its low budget, transcending its limitations.
The latter is what we get here. In the world of low budget film-making, there are a few "cheats" that can be used to make up for a lack of sumptuous screen images. One is great acting. Another is great writing. We are not treated to either of those in DUNGEON OF HARROW.
But we are treated to a creepy, hallucinatory atmosphere which is quite effective, and gives the viewer a bang for the buck infinitely out of proportion with its tiny budget. Remember, this is (to speak simplistically) a period Gothic horror film shot in Texas in 1963 for a budget under $50,000. Keeping that in mind, the filmmakers and actors have come up with quite a laudable final product. Fans of CARNIVAL OF SOULS can expect similar chills on a small budget, though COS is a much better film.
For a couple of bucks, or in a cheap DVD box set, this film is well worth your time if you like late show type horror thrills.
UPDATE: This film is in the Public Domain. Readily available on YouTube or other streaming video options for free.