You can watch it from the Internet Archive:
or at googlevideo.
1000 Misspent Hours gives it a negative review. Wild Realm Reviews sees it in a more positive light:
This is a remarkable film when compared to standard schlock sci-fi from the USA in the same year. It was the first full color Japanese science fiction film, not just a B film, & while it certainly is a camp treasure for today's viewers, it was a serious film in its day
6/15/2009: Classic Sci-Fi Movies has a review that says it
is historically significant as the first Japanese sci-fi movie shot in color -- just months before Toho's Radon was released. Unlike Rodan, however, the english dubbed version was not a re-edit, but the original Japanese director's cut.