THIS REVIEW CONTAINS SPOILERS I will lead that I have a great love for the classic super robots genre and this series caters directly to that. Unfortunately, it really has nothing to offer to anyone else outside of that. This very short run series was intended as a showcase of the different Go Nagai super robot shows with a special introduction of a new robot at the end and provides no real substance beyond that. The story is a typical heroes rescue a damsel in distress so there is nothing special here. Unfortunately, it does end in a cliff hanger which is a real shame as it couldhave easily been wrapped up with 1 more short episode. Had it also included a quick prequel episode leading up to the first as well would have made it a much more complete series.

There are no voice overs in it, only the music and sound effects.
While dialog was likely left out due to budget, I found it to be for the best as any dialog would have distracted away from the action and music.
The sound effects are very close to what might be recalled from each of the original shows for each robot.
The music is basically a collage of the intro theme songs for each of the robots with the songs jumping about as each new one is introduced. Given the patchwork nature of that, I found it to work well.

While all the character images were spot on, the overall animation art I found lacking. While decent, the budget constraints clearly showed.

As a fan of the genre and someone familiar with most of the shows, this short series brought a Marvel's Avengers moment to all those classic characters finally getting together. For that reason alone, despite its other shortcomings, loved it.

Finally, for those unfamiliar with the characters, as most are 40+ years old now and somewhat obscure, the following is a list of the shows (not characters) that provide cameos:
Mazinger Z
Great Mazinger
Mazinkaiser
God Mazinger
UFO Robot Grendizer
Getter Robo G
Shin Getter Robo
Steel Jeeg
Psycho Armor Govarian
Groizer X