Well, I think there have been enough reviews of this movie from a quality perspective. However, I have yet to see a review that accurately described the bad content in this film, so I thought I might as well write a review.
Superman is not an overly gratuitous film. It shows quite a bit of restraint as far as violence, language and sexual behaviour are concerned, but it is not squeaky clean. There are about ten curses in this film (ranging from d-words and h-words to a scarcely audible s-word). Lex Luthor's girlfriend wears VERY revealing clothing on more than one occasion which shows off quite a bit of cleavage. These scenes are fairly brief, but very noticeable. Lois Lane and Superman share a few veiled innuendos in one scene, but nothing I felt too uncomfortable with. Lois Lane asks Superman at one point what color her underwear are (he can see through anything, remember?) and he tells her that they are pink. Superman is shown completely nude from the front as a baby. Thankfully, grown-up Superman wears a jock-strap underneath his tights so that the suit is not as immodest as it could be. In one scene played for laughs, Lex Luthor's girlfriend lies out in the middle of the road as though she has fainted distracting some soldiers from their duty. In their attempts to "revive" her, one soldier sticks his head on her chest (mildly suggestive) and another volunteers to perform CPR (implied strongly, but not shown). The violence is handled well, but may be too intense for some younger viewers. For example: Lex Luthor pushes a man out in front of a fast-moving train. The death is not shown. However, the man screams loudly and the hat he was wearing is shown lying beaten up on the ground afterwards. SUMMARY: A nice classic film for most of the family. You might want to fast-forward the parts with Lex Luthor's girlfriend.