I'll be dividing this review in Story, Art and Characters, ending of course with a conclusion.
[STORY]: Great Mazinger starts right where Mazinger Z left wich is not to say much because Mazinger Z just finished from one chapter to another. We found ourselves again following the young Kouji Kabuto and his friends in their fight to stop the evil forces of Dr. Hell. But this won't be the main focus of the story because Great Mazinger actually gives us the conclusion to the seemingly endless fight between Mazinger Z and Dr. Hell's army. After this we are presented to a new enemy, the Mycenae Empire,
an ancient civilization that wants to conquer the world. With this new enemy we are also presented with a new protagonist Tetsuya Tsurugi, the pilot of the recently created Great Mazinger. As you could expect the story continues with a series of fights between Great Mazinger and the Mycenae Empire, but this time we do have a proper conclusion to the story.
Although the monster of the week formula is repeated in this new series it is much less exploited. And having a proper ending this time around is a welcome addition (not to count the ending to Mazinger Z)
[Art]: Well, there's not much to talk about in this regard. You kinda like it or not, i myself really enjoy the expressiveness of the drawings made by Go Nagai. The action is perfect, over the top powers with super creative designs are all you need to enjoy a good fight.
[Characters]: Here is were the manga drags the most, apart from the definig characteristics of each character you are not given too much reason to care. For the most part they end up being one-dimensional characters with no other objective than to being bad ass, funny or evil.
In conlusion Great Mazinger is an improvement from it's predecessor Mazinger Z, but it still misses some shots. I'd say that if you liked Mazinger Z or you like good old mechs you give it a try. If you haven't already readed Mazinger Z i would recomend you to go and read that one before starting this one.