I recently watched the Donner cut of Superman 2. The original was so cheesy that even watching it when I was little made me think Superman was kind of not right for the screen. The Donner cut made it a little better, but then he flew around the world and turn back time negating the events of the movie which ultimately left the entire thing pointless, again.
In that time, Superhero movies were in their infancy, so I give them leeway because of it. But now, we are neck deep in superhero movies and their sequels, sequels to those sequels, television shows, and superhero film spin offs to television shows. Man of Steel had a lot riding on it because Superman has been kind of a letdown in popular media. They tried to reboot him with Superman Returns, but it was boring, and he just fought a mountain and stalked Lois Lane, or had to explain himself to Lois like a boyfriend who had to justify hanging out with his friends without her. Lots of complaints about Man of Steel have come up, and they're from people who should stop breathing with their mouths open.
Too Much Destruction
What a lot of critics are saying is that there is too much damage done to cities and to people in the film. If you base this on Superman 2, where the biggest thing destroyed was a bus that flew a foot off the ground into Superman, then I guess you're right. But when you read the comics, watch the cartoons, this amount of destruction is a comic norm. You think that when superheroes and supervillains fight in a city they aren't going to destroy a lot of real estate? The Avengers sort of destroyed a lot, but most of the time was just aliens riding around on their Jet-ski's with no real objective other than to be attacked by the superheroes (Not you Hawkeye or Black Widow). This movie finally showed what superheroes fighting were supposed to look like. When Superman punched he broke the sound barrier. My childhood inside was overwhelmed with how bad I've waited to see a Superman fight done right.
Not Enough Character Development
Complaints are coming in that Superman's character wasn't that developed. People who say this must have spent the first half of the film in the bathroom because they slammed their 64oz gut busting cherry squishy during the previews. The flashbacks and exposition of Clark Kent's life reinvented the backstory of him learning his powers, being taught to hone them by Jonathan Kent, and also when not to use them (Even his Jonathan saying he possibly should have let that bus of kids drown). We watch Clark act like a teenager who is defiant, go through emotional pain, and learn life lessons that lead him to the present time in the movie. It's a brilliant set up where we learn about him and the both sides of him and his family.
It Was Too Serious
Who cares? Superman can be serious. Sure, even the dark, gritty Batman series by Nolan had jabs of humor in it, but does that make them even better because of it? There were a few chuckle moments in this movie, but the seriousness overshadowed it. Again, bringing up Superman 2, that movie was full of chuckle moments. By chuckle, I mean "This movie is awful." Remember when Superman ripped off the cellophane "S" off of his chest and threw it at Zod's enforcer? That should have ruined the franchise. And then there was Superman 3 with Richard Pryor. What? Who thought that was a good idea?
Yes man -- "We need a Superman 3. Ideas?"
Exec -- "Wife and I just saw that funny black man, Richard Pryor. Put him in that."
Yes man -- "Ye...yeah, okay."
(Yes man looks over at group of writers wondering if the high-rise window is shatterproof.)
Superman Was Too Emotional
Imagine going through grade school knowing that you could beat everyone up, but you're bullied because you allow it because a punch could decapitate them. Imagine being the outsider for all of your life because you don't know your place or your purpose. Imagine on top of puberty, you can see through everything and you can't control it yet. Imagine you lose the person closest to you when you needed them the most. Oh, and you're also an alien. Would you not be an emotional mess of a person, let alone a God on a planet? This makes Superman become a stronger person emotionally, mentally, and even more physically as the movie progresses. He learns that there is no limit to his strengths and keeps overcoming his boundaries.
I suggest you go into this movie expecting what you've always wanted: A superhero movie done right with a hint of realism that brings you back to when your imagination wanted and hoped for more. That's what I got out of Man of Steel.