Universe, the cheapness.
The film doesn't waste any time in doing callbacks to earlier films. They recall the Lois Lane flying sequence from the first film, but with limited dialog and no internal monologue. They play into the reveal of Clark as Superman, only to erase Lane's knowledge of it with the "super kiss" from the theatrical cut of Superman 2.
Recalling such elements is a means to borrow magic from earlier films so as help us ignore the shortcomings of this one. We've already touched on the lackluster effects, but the film is still trying.
Unlike Superman 2, we have Luthor (Gene Hackman) back. Margot Kidder as Lois Lane is back. This film already feels on more solid ground as a result. Despite the frequent callbacks to previous films, the writing seems to finally strike the correct tone.
In fact, we finally get what I've been wanting since I started rewatching this series: A Lex Luthor who finally feels like part of the plot. In the 78 film, Luthor was overshadowed by Zod's powerful introduction. Yet, because of studio shenanigans, he was the primary antagonist of the film. In the follow up film, Luthor had some excellent moments, was was ultimately sidelined once more.
However, Nuclear Man hits different. He feels like someone who can easily be handled by someone such as Luthor. He it's existing as a dual or superior antagonist, but as an agent to the proper villain. We also get a proper city-destruction sequence that neither Superman 2 or 3 could adequately pull off. It works for me paradoxically, because it feels more narrow and confined. The shots are more close up, and it helps to maintain the illusion while reducing cost. This is a tired and true technique we've seen in so many B-movies, and it works here.