To this day I can't understand why so many fans regard it as better than the first film, let alone call it the greatest comic book movie of all time. It is a total mess.
I stand by my assertion that IV and I are both much better films than II.
I disagree. I've always looked at the Superman movies as getting worst with each sequel.
Superman III was too campy and had a co-star (Pryor) who was so out of place it wasn't even funny.
Superman IV: The Quest For Peace had a good idea (Superman getting rid of all nuclear weapons) but had the lamest villain of the series and bad special effects.
While
Superman II isn't perfect by ANY means, it's the only one of the Superman sequels that I can watch. I'm hoping that the proposed "Special Addition" fixes some of the flaws and adds some new stuff.
As for the reason why so many people like the first sequel, there are several reasons, IMO. First of all, Donner's elements were still noticeable in the first sequel. Second, the first sequel was the most closely connected to its predecessor (also because of Donner). Third, Terence Stamp gave a great performance as General Zod. Fourth, this film actually had Lois discover Superman's secret identity and the two had a strong romantic involvement.