I noticed there are a lot of Devilman reviews that don't get a passing grade. So I'm going to attempt to be the one that break past the marks.
Devilman is similar to other anime. There is one driving plot and characters have common traits, but Devilman has a special predicament that makes it irresistible. It has the scary demon theme, the insertion and deletion of fear, the cold hard sweat of anticipation and excitement. There are demons planning to take over the world. One man's normal life is shattered and there is no return. After pushed by his friend, he has to accept the job as Devilman. It is a dangerous ritual right at the demons' lair. He who fights the demons for eternity, slipped into darkness, protecting the world from destruction, this is Devilman. You'll find it very enjoyable.