I think the reason why certain people aren't fond of this Superman is due to the fact that the transition from the old Superman to the current Superman has never been made.
For the past few decades now, comics and superheroes have began to move away from being cheesy and aimed at kids to being more mature and more aimed at adults. This transformation reached an all-time-high in the past few years specifically since more comic book movies started to be made. Most of the big superheroes, such as Batman and Spider-Man, haven't had the problem of people not being used to a particular version of them to the same extent Superman has with MOS because they had casual transitions from cheesy to more mature. Superman did not.
Let's take Batman for example since he arguably had the best transition and that is also arguably part of the reason why he is the top dog of superheroes at the moment. We did not go directly from the campy Adam West TV series to the gritty Nolan films. We naturally got there overtime. First, we had the Burton/Schumacher franchise. With the exception of Batman & Robin, all 3 films were still darker than the Adam West series and took themselves more seriously yet they still weren't as dark as the Batman comics we know. However, they were a step in the right direction. We eventually got the right tone of the Batman of the comics with Batman Begins. Had it not been for that transition, Batman Begins might not have had the critical praise that it did. That would have possibly been the case if BB came out back in 1989.
In Superman's case, the last time we saw a proper Superman on the big screen was back in the late 70's/very early 80's and that was the Bronze Age Superman. Most people did not see the transition from that Superman to the John Byrne/Birthright Superman of the Post-Crisis comics, which is a bit more serious and more realistic in comparison. What we have instead was a giant gap between those two versions with nothing in between to create a natural transition, which wasn't the case for Batman. Sure that we had Superman Returns but that was almost a complete rehash of the first Donner film in terms of story and tone so I wouldn't count it.
