Keeping in mind that this animation was released in 1989, the production values and voice overs are pretty high quality. Having said that, the film itself is rather terrible. The plot is strikingly outlandish and the characters are strikingly undeveloped. I consider this "film" to be basically an animated porn.

While Legend of the Overfiend has a complicated plot, it falls far short of other well known anime such as Akira or Vampire Hunter D. While the violence in either of these animated movies is directly driven by the plot - especially in Akira - the violence in Legend of the Overfiend seems to have little purpose or meaning.

There are some very funny moments in Legend of the Overfiend, but once again, the characters are so cardboard that you get only a chuckle out of them and then forget about it a moment later.

All in all, I would recommend Legend of the Overfiend to anyone that has a deep curiosity about where the current state of Japanese Hentai originated from, but if you really must watch "tentacle porn", try La Blue Girl instead.