It was, as has been pointed out in some of the show reviews, a more serious program than the more popular Batman, with whom the characters sometimes integrated. The Green Hornet and his crime-fighting companion, Kato (played by the legendary Bruce Lee), were, unlike Batman and Robin, considered a menace to society. This actually helped them in their battle against crime, as it led the hoodlums and gangsters of the underworld to trust them, before the duo lowers the boom on them. Despised by society, their alter egos were more trusted, as the Green Hornet was really newspaper publisher and TV station owner Britt Reid who, according to the storyline of the radio version, was agreat-nephew of John Reid, AKA the Lone Ranger.
I remember when FX used to air this in 1996, but other than that it hasn't been seen much since its cancellation in 1967. I'm hoping for a DVD release, perhaps one coupled with a release of Batman.