A few thoughts: Look at the title and look at the picture below. You may have never seen or heard of this movie before in your life, but you know exactly what it is just from these two things alone. This is a fake trailer type of movie never meant to sustain more than 5 minutes of entertainment. There's very little to be said for it that you can't figure out on your own, but let me throw out a few things that help set this apart from others of this variety. For starters, you don't feel cheated by the title at all. The Octaman has plenty of screentime, and is given plenty of people to kill, so in the very least there's that going for it. Secondly, some of the earlier scenes in this movie are bad in the funniest sort of ways, but the humor begins to dissappear as you realize there is nothing more to this movie than just the bad "effects" and the creature itself. It just sort of happens until it's eventually over -- but luckily it ends pretty quickly at just under 80 minutes. Worth watching if you're drunk.
Who would I recommend it to? It's a pretty niche movie, but if you enjoy corny rubber suit monsters, you might like this one for its simple stupidity.