No holds barred here. I don’t like the character, I don’t like the concept. He, for a lack of better word, is overpowered for the sake of being over powered. To make matters worse, he is Space Jesus.
Superman, as a character, can literally do no wrong. He will always save the person in distress. He will always beat the bad guy. He will always prevent the apocalypse. Without fail. Reading/watching a piece of Superman media will always be the same. And to me, who moonlights as a writer, that just makes a horrible character.
There is no depth to his character, no character growth. The closest that I have seen is when writers have looked into Superman’s origins in Kansas, but it simply reinforces the idea that he is a simple country boy that will always make the right decisions. And that is almost a sin- there is never any struggle, there is the eternal knowledge

that he will prove victorious in whatever is going on.
Adding to the fact that Superman/Clark Kent is a perfect human being (to an adult, white male perspective, as I am there are reams of articles on other blogs discussing how Superman is a sexist) he has every superpower in comics. Super strength? Can fight gods hand to hand. Speed? Goes on regular foot chases with the Flash. Can fly? Of course. Laser beams? Had them when the thought was conceived. Ice powers? Frost breath that matches Mr. Freeze. Literally being invulnerable to most forms of violence? Got that in spades. They don’t call he the ‘Man of Steel’ for nothing.
This all adds up to the fact that Superman has every tool imaginable to overcome any obstacle. Due to this, the writers have two choices- make him weaker, or make him think. This ends up to 2 major weaknesses. Kryptonite, which has become a word all onto its own due to its affect on Superman, and magic. Even still, with those two weaknesses, as soon as whatever is weakening him is turned off/broken, he just punches the guy, and the battle is won.
One last point. One that really seals the deal for me as a character, and a hero: Superman is a stupid person.
There. I said it. Despite the super speed, strength, and being a perfect person, he is a moron. As it is literally the only way to beat a god, writers fell on the idea that Superman cant think himself out of a box. This has weakened him to the point that Superman has to be saved by the Justice League on more than one occasion.
All told, I think Superman is a terrible character. As a person, and as a protagonist, he is a horrible piece of fiction.