What a total lack of understanding of how character development works.
So Superman dies, and everything about that falls completely flat. There's no foreshadowing at all to prepare us for the moment, and when it comes they haven't established why a sacrifice is the only choice, so during his lame goodbye speech there's no way you can be invested in the scene, because all you're thinking is, why does he have to die? Can't he just stab him and not die? And haven't we established three seconds ago that he can't be the one doing the stabbing, because he can't even lift the spear without passing out? Oh apparently he can pick it up, and fly. Just give it to wonder women, you don't have to do it yourself. Oh I guess It's too late, you already stabbed him. Good job man, you did it. Let go of the spear now. Just leave. Let go dude. Ok now Doomsday grabbed you and stabbed you. Dumb. Oh you're impaling yourself further into the spike, so you can make the spear penetrate all the way through? Why? You're taking the kryptonite out of his body. You fucking idiot. This is your great sacrifice, you stupid idiot. Jesus christ. I don't believe for a second that you're actually dead. So, just stop pretending and get up now. No, you're really going to just stay dead? Ok so we're at your funeral now, wow I guess you really want to make a point that you're actually dead for real here. Ok 15 minutes of funeral stuff. Guess they're serious about this. Ok now this farce is finally coming to an end... and the dirt moves.... Fuck you.