The opening theme songs to several Super Robot series are just astounding. Great Mazinga has one of them. I think I may like it more than Mazinga Z's theme, in fact. I love most everything about Great Mazinga, and think the design is actually better than Z's as well. I do think Z is the better series, mostly due to the cast and Koji Kabuto himself.
But that's a post or article for another time. I still need to get the DVD sets of Mazinga Z now, I do hope they release this series as well, since they flow right into each other.