Reeve was awesome.. while anyone else wearing that suit might look silly, he did not.. it was all about how he carried himself. I read that he pretty much behaved like he was wearing a regular three-piece business suit - he was neither ashamed of it nor did he try draw to attention to it. And I think the approach to the SFX had the same quality.. they used every technique they could imagine and then some to bring it to life, and it feels often like Superman exists in real world, and though some shots are dated (particularly the blatant blue-screen shots where the city is out of focus behind Reeves) most of them hold up well, and I like them better than shots in a lot of newer superhero films. I love the whole scene where he first takes off after Lois (when the guy compliments him on the nice outfit) that there is a quick cut that one suspects hides the change to the effect shot, but this cut is so well-placed it actually adds to the momentum of the scene... its fantastic. In the scene where Superman brings the robber (who climbs buildings) to the cop was done with a harness (you can see it almost underneath the costume) I love it anyway because it shows that he exists in within the environment. And the script has him not just saving people and stopping earthquakes, it has him saving trains, buses, and the entire San Andreas Fault. They obviously reached high and then worked their asses off to bring it to life. Most superhero hero films since have been tame by comparison, not the least of which is Superman Returns
But, above all the film had conviction and heart. They make for any of the "dated" aspects.