I've been watching one episode of L&C a night before bed for a while now (it's perfect for that, which I suppose is as much a criticism as a complement). I purchased seasons 2, 3 and 4 consecutively so I'm watching them in order....anyway, Cain's Superman has grown on me. And by the time I got to the third season episode, 'Super Mann', he finally convinced me he was Superman, and I started looking at the character a different way.
A lot of it is to do with the writing and special effects. If Superman is written badly, or the effects are unconvincing, they are going to make Cain look bad whatever he does. But a lareg part of it is because Cain is up against pathetic bad guys in the first two seasons (except for Lex), most of which are simply comedy double acts. A man is judged by his enemies.
When we get to season three however, not only are the stories bigger in scope, not only have the effects improved substantially, but the bad guys are finally bad. Evil, menacing. A threat. These are villains that only Superman can stop, whereas before the police or even Lois and Jimmy could conceivably stop the bad guys of previous seasons.
By the time we get to the episode 'Super Mann', we get the pure comicbook conceit of suspended animation Nazis trying to unleash the Fourth Reich. Much, much better villains than typical L&C ones. You can't go wrong with Nazis as the bad guys, they don't even require a build up. We all know how great a threat Nazis are. And only Superman can stop them - but they trick him by luring him to an unexploded WWII bomb that explodes in his face. He survives, but is covered in radioactive particles and has to stay in a glass cell for 300,000 years. Obviously helpless to stop the Nazis conquering Metropolis and the world.
Now that's more like it-!
Even better, Lois thinks of a last minute way to get Supes free....he can fly into the suns gravitational pull and it will suck the radioactive material out of him...but it will take hours to get to the sun and back, and he doesn't even know if he can escape the sun's gravity once he is there.
While he's up there, the Nazis threaten the world leaders, and when they fail to comply, the Nazis are about to explode bombs all over thw world...
...obviously you know what happens next, but the fact that the story is built up so well, the threat is huge and the effects are suficient, Superman becomes a much more dynamic, heroic, powerful and exciting character in this episode. By the end of it, I looked at Cain completely differently, for the first time I thought, "Whoa, he really is Superman."
So I've retracted my views on Cain being a lame Superman.
And also as you can see in the image below, as the series progresses, he looks a bit older, and no loner the Superboy of the early episodes.
http://media.monstersandcritics.com/articles/1177586/article_images/loissupermanandjimmy.jpg