I really enjoyed Superman's restraint in the movie. This is one particular element of the character that they nailed quite well.
Any other hero would have destroyed Batman, killed Lex for showing him photos of his tortured Mother, and would have let Lex die by the creature he created. But not Superman. I know we can ***** and moan that Batman won the fight. However, it's Superman's restraint and his want to plead to Batman to team up and go after Lex, but Batman isn't having any of it, that really makes Superman shine. This is Superman's first exposure to Kryptonite as well. Yet, he took it. Yeah, he fought back so he wouldn't just straight up die, but he never used brutal force against Batman. He played Batman's game.
It's a good point. I think a lot of people glossed over it because
the fight was disappointing in execution as well as result for Superman fans. I know some were critical of the way he told Lois that he had to go to Gotham but putting yourself in his shoes I thought his reactions were both human and what you'd expect from Superman. He was distraught like a human being would be but also pure enough to not resort to murdering Batman which would have been easy. He was even willing to swallow his pride and apologize to appeal for help on behalf of his mother.
I think the saddest part of the reception to this movie is that almost all of the ingredients are there. They're just not allowed to breath because the editing and pacing are so poor. Somewhere within what they shot is a really good movie that a better director would have put together.