Critical reception
Godzilla vs. Megalon was released theatrically in America on May 9, 1976, though the San Francisco Chronicle indicates that it opened there in June, and The New York Times indicates that it opened in New York City on July 11. New York Times film critic Vincent Canby, who a decade before had given a negative review to Ghidorah, the Three-Headed Monster, gave Godzilla vs. Megalon a generally positive review. In his review on July 12, 1976, Canby said, "Godzilla vs. Megalon completes the canonization of Godzilla...It's been a remarkable transformation of character - the dragon has become St. George...It's wildly preposterous, imaginative and funny (often intentionally). It demonstrates the rewards of friendship, between humans as well as monsters, and it is gentle."

Legacy
Godzilla vs. Megalon has attracted the ire of many Godzilla fans in the decades since its original release. The film contributed to the reputation of Godzilla films in the United States as cheap children's entertainment that should not be taken seriously.[4][5] It's been described as "incredibly, undeniably, mind-numbingly bad"[6] and one of the "poorer moments" in the history of kaiju films.[5]

In particular, the special effects of the film have been heavily criticized. One review described the Godzilla costume as appearing to be "crossed with Kermit the Frog"[5] and another sneeringly compared it to Godzilla vs. Gigan, stating that it did "everything wrong that Gigan did, and then some." However, most of the criticism is of the lack of actual special effects work, as most of it consists of stock footage from previous films, including Godzilla vs. Gigan and Ghidorah, the Three-Headed Monster, and a few pieces of effects work has garnered praise, specifically a scene where Megalon breaks through a dam and the draining of the lake.[4]

The other aspects of the film have been similarly skewered. The acting is usually described as flat and generally poor, and as not improving, or sometimes, worsening, the already weak script.[4] One part of the film, on the other hand, has garnered almost universal praise: Godzilla's final attack on Megalon, a flying kick. It has been called the saving grace of the film[6], and was made famous by the mock exclamations of shock and awe displayed on Godzilla vs. Megalon's appearance on Mystery Science Theater 3000 (Through the end of season three to the middle of season five, that clip would be shown at the opening of each show). Despite all this, the film is also one of the most widely seen Godzilla films in the United States — it was popular in its initial theatrical release, largely due to an aggressive marketing campaign, including elaborate posters of the two title monsters battling atop New York City's World Trade Center towers, presumably to capitalize on the hype surrounding the Dino De Laurentiis remake of King Kong, which used a similar image for its own poster.[4]

Despite the criticism that the film has taken over the years, Godzilla fans consider the film a cult classic and at times enjoy the film despite its cheesiness. Jet Jaguar himself has a cult following placing him among the ranks of fellow kyodai heroes, such as Ultraman and Zone Fighter, with fans demanding for his return to the Godzilla series, if not, a stand alone spin-off.