It's somewhat of a novelty movie. Despite being a big mecha fan, this was simply too silly for me to really enjoy. Very little about this movie made any sense. The basic premise was seriously flawed, you don't send a large force to destroy a major threat and then just not bother to find out what happened.
The thing I remember most about this movie was that despite it being one of the most expensive live action movies ever made in japan (at the time), it's special effects were completely blown away by the C-Grade movie "Robo-Jox" that came out here, I think in the same year.